Categories
AJAX Angular CSS CSS3 HTML HTML5 JavaScript jQuery NodeJS UI

UI Architect Interview Questions and Answers

what is tail call optimization ?
TCO (Tail Call Optimization) is the process by which a smart compiler can make a call to a function and take no additional stack space.

Recursive function approach has a problem. It builds up a call stack of size O(n), which makes our total memory cost O(n). This makes it vulnerable to a stack overflow error, where the call stack gets too big and runs out of space. Tail Cost Optimization (TCO) Scheme. Where it can optimize recursive functions to avoid building up a tall call stack and hence saves the memory cost.

what is Map, Set, WeakMap and WeakSet ?
Map is a collection of keyed data items, just like an Object. But the main difference is that Map allows keys of any type.

A Set is a collection of values, where each value may occur only once means it will contain unique set of keys. 

WeakSet is a special kind of Set that does not prevent JavaScript from removing its items from memory. WeakMap is the same thing for Map.
WeakMap does not support iteration and methods keys(), values(), entries(), so there’s no way to get all keys or values from it.

Map – is a collection of keyed values.

The differences from a regular Object:

Any keys, objects can be keys.
Iterates in the insertion order.
Additional convenient methods, the size property.
Set – is a collection of unique values.

Unlike an array, does not allow to reorder elements.
Keeps the insertion order.
Collections that allow garbage-collection:

WeakMap – a variant of Map that allows only objects as keys and removes them once they become inaccessible by other means.

It does not support operations on the structure as a whole: no size, no clear(), no iterations.
WeakSet – is a variant of Set that only stores objects and removes them once they become inaccessible by other means.

Also does not support size/clear() and iterations.
WeakMap and WeakSet are used as “secondary” data structures in addition to the “main” object storage. Once the object is removed from the main storage, if it is only found in the WeakMap/WeakSet, it will be cleaned up automatically.

how to do peer to peer communication in ANgular ?

what is directive & components in angular ?

if loop functions are removed from script, how can you achieve same functionality ?

how to drop both data and collection in mongodb ?

what is generic types in Typescript ? advantages ?

how to define custom types in Typescript ?

how to capture the process specific exceptions in NodeJS ?

how do you print name of file currently executing in NodeJS ?

how to use custom pipes in Angular ? can you pass additional parameters in custom pipes ?

what is the max data can be stored in a mongodb document ?

how to acheieve variable length documents in mongodb ?

how do you set autoincrement field in mongodb ?

what is the difference between throttling & debouncing ?
Throttling enforces a maximum number of times a function can be called over time. As in “execute this function at most once every 100 milliseconds.”
Debouncing enforces that a function not be called again until a certain amount of time has passed without it being called. As in “execute this function only if 100 milliseconds have passed without it being called.”

what is event bubbling ? how to stop ?
what is digest cycle in angularJS ?
how to stop propgation ?
what is interpolation ? how does it work ?
what is shadow dom ?
what is webworker ?
how to cache the page/data in HTML 5 ?
how to give offline view expereince in HTML5 ?
what is lazyloadng? how it works ?
what are pure / impure pipes ?
what is redux ? how does it work ?
unit testing code coverage how to check ?
what tool used for unit test ?
streaming , how does it work ?
any custom video/audio player developed?
how does cache works in HTML5 ?
what is method chaining ?
difference between canvas vs SVG ?
what is XSS and how to avoid it ?

difference between Responsive and Adaptive design ?
diff b/w flexbar & grid designs ?
what is cors ? how to allow ?
symmetric & asymetric keys ?
scope usage in OAuth token ?
explain component lifecycle
how to use service in Angular ?
what is event emitters ?
latest ECMA version ?
INPUT & OUTPUT variables usage in Angular
explain Digest Lifecycle in Angular ?
difference between Angular 1.x & Angular 2.x
what is SASS & SCSS ?
what is ViewChild ? OR ViewCildren ?

Explain the following :

Directives,
decorators,
Services,
Modules,
Data Binding,
Components,
Filters,
DOM ,
Events ,
Routing,
Dependency injection.

Categories
Agile AJAX Angular CSS CSS3 HTML HTML5 JavaScript jQuery NodeJS UI

Javascript / UI / Angular Architect Questions and Answers

1.Difference between var let and const. ?

a. Var is hoisted in JS, let and const are not hoisted.

b. Let, const are block level, var is function level The candidate has to tell at least one of these apart from any other difference he tells.

2. What is a closure and how does it work

a. A closure is an inner function that has access to the outer (enclosing) function’s variables—scope chain.

A closure is an inner function that has access to the outer (enclosing) function’s variables—scope chain.

3. What is a JavaScript class

a. ES 6 standard introduced classes in JS, which internally use the prototypal approach to implement Class .

4. How does JS implement inheritance

a. JS uses prototypal inheritance in which objects inherit properties from other objects (or) JS uses prototypes to implement inheritance

5. What is the difference between == and === in JS

a. == checks only for the value, where === checks for both value and data type

6. What is the use of hasOwnProperty method in JS

a. This method returns true, only when the passed property is present directly on the object.

7. Explain call, apply and bind

a. Call and apply are used to invoke a method, by setting the context of ‘this’ keyword. Call takes comma separated individual parameters, and apply takes array of parameters as arguments

b. Bind method does the same operation as call and apply, but returns a new function definition instead of invoking the method

8. What is ‘arguments’ keyword in JS

a. Arguments is a special property in every function, that holds all the parameters passed to that function. Its an array-like object.

9. What is arrow function

a. Arrow function is introduced in ES 6 standard of JS, and does implicit binding of this property.

10. What are benefits of TypeScript

a. * TS provides type safety for the variables

Skills checked:

JS core – Intermediate / Advanced

  1. What is a closure and how it works in JavaScript
  2. What is a ‘hosting’ , How this works in JavaScript ?
  3. call, apply and bind with example
  4. Event bubbling and Event capturing
  5. event delegation
  6. prototypical inheritance / prototypical chain
  7. strict mode and usual mode
  8. What is EventLoop?

ECMA

  1. Difference between var, let and const?
  2. What is a promise and how it works?
  3. What is a arrow function and its difference from function syntax?
  4. Generator and how it works
  5. JS modules, export and export default
  6. async/await

Angular – Intermediate / Advanced

  1. Virtual DOM concept.
  2. Subscribe, Observables and Promises.
  3. Different ways of data bindings.
  4. Sequence of Angular Lifecycle Hooks
  5. Routing
  6. Reactive Forms.

React JS and Redux – Novice / Intermediate

  1. Virtual DOM concept.
  2. Explain lifecycle of React component.
  3. Difference between state and props.
  4. Redux
  5. Role of reducer

HTML – Novice / Intermediate

  1. What is a Doctype?
  2. quirks mode and standart mode
  3. new features in html5
  4. Html storage Localstorage and sessionstorage

CSS – Novice

  1. Difference between adaptive and responsive design?
  2. What is a repaint and reflow?
  3. Media query.
  4. Layout Methodology.
  5. How browser search selector?

Networking – Intermediate

  1. What is REST?
  2. REST principles.
  3. Difference between POST and PUT requests

Design Patterns – Advanced

  1. Factory Patterns
  2. Singleton Patterns

Unit testing

  1. TDD/BDD
  2. jasmine/karma

Processes

  1. GIT
  2. Code review process and tools
  3. CI/CD
  4. SOLID
  5. SCRUM
  6. Webpack
  7. IDE

Categories
Angular JavaScript NodeJS UI

BARCO – MEAN Architect – NodeJS developer Interview Questions and Answer

BARCO – MEAN Architect – NodeJS developer Interview Questions and Answer

what is tail call optimization ?
TCO (Tail Call Optimization) is the process by which a smart compiler can make a call to a function and take no additional stack space.

Recursive function approach has a problem. It builds up a call stack of size O(n), which makes our total memory cost O(n). This makes it vulnerable to a stack overflow error, where the call stack gets too big and runs out of space. Tail Cost Optimization (TCO) Scheme. Where it can optimize recursive functions to avoid building up a tall call stack and hence saves the memory cost.

what is Map, Set, WeakMap and WeakSet ?
Map is a collection of keyed data items, just like an Object. But the main difference is that Map allows keys of any type.

A Set is a collection of values, where each value may occur only once means it will contain unique set of keys. 

WeakSet is a special kind of Set that does not prevent JavaScript from removing its items from memory. WeakMap is the same thing for Map.
WeakMap does not support iteration and methods keys(), values(), entries(), so there’s no way to get all keys or values from it.

Map – is a collection of keyed values.

The differences from a regular Object:

Any keys, objects can be keys.
Iterates in the insertion order.
Additional convenient methods, the size property.
Set – is a collection of unique values.

Unlike an array, does not allow to reorder elements.
Keeps the insertion order.
Collections that allow garbage-collection:

WeakMap – a variant of Map that allows only objects as keys and removes them once they become inaccessible by other means.

It does not support operations on the structure as a whole: no size, no clear(), no iterations.
WeakSet – is a variant of Set that only stores objects and removes them once they become inaccessible by other means.

Also does not support size/clear() and iterations.
WeakMap and WeakSet are used as “secondary” data structures in addition to the “main” object storage. Once the object is removed from the main storage, if it is only found in the WeakMap/WeakSet, it will be cleaned up automatically.

how to do peer to peer communication in ANgular ?

what is directive & components in angular ?

if loop functions are removed from script, how can you achieve same functionality ?

how to drop both data and collection in mongodb ?

what is generic types in Typescript ? advantages ?

how to define custom types in Typescript ?

how to capture the process specific exceptions in NodeJS ?

how do you print name of file currently executing in NodeJS ?

how to use custom pipes in Angular ? can you pass additional parameters in custom pipes ?

what is the max data can be stored in a mongodb document ?

how to achieve variable length documents in mongodb ?

how do you set auto increment field in mongodb ?

Categories
AJAX JavaScript

Chart JS canvas dynamic draw chart and clear using AJAX based JSON data

Chart.js  :  How to Clear canvas after drawing a chart based on the dynamic data received from AJAX based JSON response data ?

Normally  if you try to draw a new dynamic chart after an AJAX request based on the JSON data received than the the graph starts jumping around and gets fuzzy between the grid lines. This issue happens every time when the JSON data has changing datasets based on the AJAX cal request. 

To sort out this issue , you need to destroy the chart before redrawing with new dataset. 

create a global variable and use that variable while creating chart :

myChart:

and use this variable to assign chart instance, before assigning the chart instance make sure to check if any previous chart instance is available with the global variable, if exist than clear and destroy the chart distance : 
createChart: function() {
var ctx = document.getElementById(myChart); // check if any existing chart instance data is available and destroy
if(this.myChart instanceof Chart){
this.myChart.clear();
this.myChart.destroy();
} //draw new chart
this.myChart = new Chart(ctx, {
type: this.chartData.type,
data: this.chartData.data
});
}
I have taken the vue.js implementation with chart.js as the example in above scenario. 
Categories
CSS CSS3 HTML HTML5 JavaScript jQuery

HCL – Web / UI Developer – interview questions and answer – HTML5 , CSS3 , JS & jQuery

1) Explain about HTML5 local storage ?
There are two ways to store data in HTML as objects locally :

  1. localStorage – store data  across session acess
  2. sessionStorage – storing data for current session only

Data will be stored in key/value pair format.
example:
localStorage.empid=”420″;
sessionStorage.companyname = “SHARAG INFOTECH”;
2)  explain CSS media queries ?
CSS media queries are used to develop responsive templates for different layout of screen, print, mobile , tablet or any other resolutions
CSS media queries can be added in 3 ways as like CSS style sheet :

  1. Internal stylesheet :  <style type=”text/css”>
    @media only screen and (max-width: 600px){
    /* rules apply to the device resolution is 480px or less  */
    }
    </style>
  2. Imported stylesheet :   @import “tablet.css”   (min-width: 800px) and (max-width: 1200px);
  3. External stylesheet:  <link rel=”stylesheet” type=”text/css” href=”deskto.css” media=”screen and (min-width: 1200px), print and (min-resolution: 300dpi)” />

3) explain css inheritance ?
Inheritance propagates property values from parent elements to their children. The inherited value of a property on an element is the computed value of the property on the element’s parent element. For the root element, which has no parent element, the inherited value is the initial value of the property.
A property can also be explicitly inherited by using the inherit keyword in property.
CSS inheritance example:
class inheritance for an HTML tag :
<div class=”firstClass secondClass thirdClass fourthClass ” > </div >
CSS property inheritance from parent :
p {
color: #000;
}
p a:link {
color: inherit;
}
and using LESS method for inheritance example:
//through variable
@color: #123456;
#emp {
color: @color;
}
div {
color: @color;
}
//through class name calling [MIXINS]
.rounded-corners (@radius: 2px) {
-webkit-border-radius: @radius;
-moz-border-radius: @radius;
-ms-border-radius: @radius;
-o-border-radius: @radius;
border-radius: @radius;
}
#navtable {
.rounded-corners;
}
#maintable {
.rounded-corners(5px);
}
4) what is javascript inheritance ?
In simple terms, inheritance is the concept of one thing gaining the properties or behaviours of something else.
Inherited children inherit their parent’s behaviour To say A inherits from B, is saying that A is a type of B.
In JavaScript You must use a special object called prototype.
function Animal() {}; // This is the Animal *Type*
Animal.prototype.eat = function () {
alert(“All animals can eat!”);
};
function Bird() {}; // Declaring a Bird *Type*
Bird.prototype = new Animal(); // Birds inherit from Animal
Bird.prototype.fly = function() {
alert(“Birds are special, they can fly!”);
};
The effect of this is that any Birds you create (called an instance of Bird) all have the properties of Animals
var aBird = new Bird(); // Create an instance of the Bird Type
aBird.eat(); // It should alert, so the inheritance worked
aBird.fly(); // Important part of inheritance, Bird is also different to Animal
var anAnimal = new Animal(); // Let’s check an instance of Animal now
anAnimal.eat(); // Alerts, no problem here
anAnimal.fly(); // Error will occur, since only Birds have fly() in its prototype
5) explain javascript associative array ?
Associative arrays are where we can associate a key string with a value string
JavaScript objects are also associative arrays.
i.e the property  emp.Name can also be read by calling emp[‘Name’]
We can access each property by entering the name of the property as a string into the array
it refers to accessing the DOM elements of HTML also [as object or associative array]
6) explain JS Namespace ?
Namespacing is a technique employed to avoid collisions with other objects or variables in the global namespace
and also helps to organize blocks of functionality into easily manageable groups that can be uniquely identified.
JavaScript doesn’t  builtin support of namespacing but using objects and closures we can achieve a similar effect.
javascript Namespacing patterns :
1)    Single global variables :
var myApplication =  (function(){
function(){
/*…*/
},
return{
/*…*/
}
})();
2)    Object literal notation :
var myApplication = {
getInfo:function(){ /**/ },
// we can also populate our object literal to support
// further object literal namespaces containing anything
// really:
models : {},
views : {
pages : {}
},
collections : {}
};
3)    Nested namespacing :
var myApp =  myApp || {};
// perform a similar existence check when defining nested
// children
myApp.routers = myApp.routers || {};
myApp.model = myApp.model || {};
myApp.model.special = myApp.model.special || {};
// nested namespaces can be as complex as required
4)    Immediately-invoked Function Expressions :
// an (anonymous) immediately-invoked function expression
(function(){ /*…*/})();
// a named immediately-invoked function expression
(function foobar(){ /*..*/}());
// this is technically a self-executing function which is quite different
function foobar(){ foobar(); }
5)   Namespace injection :
// define a namespace we can use later
var ns = ns || {}, ns2 = ns2 || {};
// the module/namespace creator
var creator = function(val){
var val = val || 0;
this.next = function(){
return val++
};
this.reset = function(){
val = 0;
}
}
creator.call(ns);
// ns.next, ns.reset now exist
creator.call(ns2, 5000);
// ns2 contains the same methods
// but has an overridden value for val
// of 5000
for more details on namespace read http://addyosmani.com/blog/essential-js-namespacing/
7) explain Jquery live and bind methods ?
.bind() attacheds events to elements that exist or match the selector at the time the call is made.
Any elements created afterwards or that match going forward because the class was changed, will not fire the bound event.
$(‘img’).bind(‘click’, function(){…});
.live() works for existing and future matching elements.
Before jQuery 1.4 this was limited to the following events:
click, dblclick mousedown, mouseup, mousemove, mouseover, mouseout, keydown, keypress, keyup
$(‘img’).live(‘click’, function(){…});
8) what is bootstrap ?
Bootstrap is an open-source Javascript framework developed by the team at Twitter.
It is a combination of HTML, CSS, and Javascript code designed to help build user interface components.
Bootstrap is Sleek, intuitive, and powerful mobile first front-end framework for faster and easier web development.
Bootstrap was also programmed to support both HTML5 and CSS3
Bootstrap is a CSS and Javascript framework that is used within your HTML. Bootstrap provides more advanced functionality to your web site.
More details http://getbootstrap.com
9) type of webservice ?
there are two types of web service….1. SOAP [Simple Object Access Protocol] Webservice and 2. RESTful [REpresentational State Transfer] Webservice.
SOAP is a messaging protocol , REST is a design philosophy , not a protocol.
SOAP:
you define your interface in a .wsdl file, which describes exactly which input parameters are expected and how the return values will look like
there are tools to generate the .wsdl files out of java class hirarchies. JAXB for example
there are also tools to generate java objects/classes as part of eclipse for example (don’t know the name in the moment).
SOAP is very strict. Every request is validatet against the wsdl before processing.
A good but not so easy to start with framework for SOAP WS is Apache CXF
REST (no hands on experience up to now, feel free to correct and improve 😉 ):
a way to access a webserver or web application to retrieve data from or send to it.
it’s only negotiated, how it is accessed.
common is something like this http://server.domain.com/app/type/id=123 to retrieve object of type type with id=123
very intuitive, but no automatic validation of requests.
The main advantages of REST web services are:
Lightweight – not a lot of extra xml markup
Human Readable Results
Easy to build – no toolkits required
SOAP also has some advantages:
Easy to consume – sometimes
Rigid – type checking, adheres to a contract
Development tools

Categories
HTML PHP

ALL CSS Interview question and answer

1. What is CSS?
CSS stands for Cascading Style Sheets and is a simple styling language which allows attaching style to HTML elements. Every element type as well as every occurance of a specific element within that type can be declared an unique style, e.g. margins, positioning, color or size.
2. What are Cascading Style Sheets?
A Cascading Style Sheet (CSS) is a list of statements (also known as rules) that can assign various rendering properties to HTML elements. Style rules can be specified for a single element occurrence, multiple elements, an entire document, or even multiple documents at once. It is possible to specify many different rules for an element in different locations using different methods. All these rules are collected and merged (known as a “cascading” of styles) when the document is rendered to form a single style rule for each element.
3. How do I center block-elements with CSS1?
There are ways of centering block level elements:
By setting the properties margin-left and margin-right to auto and width to some explicit value:
BODY {width: 30em; background: cyan;}
P {width: 22em; margin-left: auto; margin-right: auto}
In this case, the left and right margins will each be four ems wide, since they equally split up the eight ems left over from (30em – 22em). Note that it was not necessary to set an explicit width for the BODY element; it was done here to keep the math clean.
4.If background and color should always be set together, why do they exist as separate properties?
There are serveral reasons for this. First, style sheets become more legible — both for humans and machines. The background property is already the most complex property in CSS1 and combining it with color would make it even more complex. Second, color inherits, but background doesn’t and this would be a source of confusion.
5. What is class?
Class is a group of 1) instances of the same element to which an unique style can be attached or 2) instances of different elements to which the same style can be attached.
6. What is grouping?
Grouping is gathering into a comma separated list two or more selectors that share the same style or into a semicolon separated list two or more declarations that are attached to the same selector .
1. The selectors LI, P with class name .first and class .footnote share the same style, e.g.:
LI {font-style: italic}
P.first {font-style: italic}
.footnote {font-style: italic}
To reduce the size of style sheets and also save some typing time they can all be grouped in one list.
LI, P.first, .footnote {font-style: italic}
7. What is external Style Sheet? How to link?
External Style Sheet is a template/document/file containing style information which can be linked with any number of HTML documents. This is a very convenient way of formatting the entire site as well as restyling it by editing just one file. The file is linked with HTML documents via the LINK element inside the HEAD element. Files containing style information must have extension .css, e.g. style.c ss.
<LINK rel=stylesheet type=”text/css” href=”style.css“>
8. Is CSS case sensitive?
Cascading Style Sheets (CSS) is not case sensitve. However, font families, URLs to images, and other direct references with the style sheet may be.
9. What is CSS rule ‘ruleset’?
There are two types of CSS rules: ruleset and at-rule. Ruleset identifies selector or selectors and declares style which is to be attached to that selector or selectors. For example P {text-indent: 10pt} is a CSS rule. CSS rulesets consist of two parts: selector [ e.g. P ] and declaration [ e.g. {text-indent: 10pt}] .
P {text-indent: 10pt} – CSS rule (ruleset)
{text-indent: 10pt} – CSS declaration
text-indent – CSS property
10pt – CSS value
10. ‘Fixed’ Background?
There is the possibility to use the HTML tag bgproperties=”fixed”, but that is IE proprietary, and dependent upon the ‘background’ attribute (deprecated in HTML4).
With CSS, you can declare the background like:
BODY {
font-family : “Trebuchet MS”, Verdana, Arial, Helvetica, sans-serif;
background-image: url(images/yourimage.gif);
background-repeat: no-repeat; /*no-tiling background*/
background-position: center;
background-attachment: fixed;
background-color: #hexcolor;
color : #hexcolor;
margin: 10px;
}
that shows a background-image in the center of the element, non-scrolling and non-repeating – in IE or NN6. NN 4.xx gets the non-repeat-part right, but stuffs the picture in the upper left corner and scrolls ..
11. What is embedded style? How to link?
Embedded style is the style attached to one specific document. The style information is specified as a content of the STYLE element inside the HEAD element and will apply to the entire document.
Note: The styling rules are written as a HTML comment, that is, between to hide the content in browsers without CSS support which would otherwise be displayed.
12. What is ID selector?
ID selector is an individually identified (named) selector to which a specific style is declared. Using the ID attribute the declared style can then be associated with one and only one HTML element per document as to differentiate it from all other elements. ID selectors are created by a character # followed by the selector’s name. The name can contain characters a-z, A-Z, digits 0-9, period, hyphen, escaped characters, Unicode characters 161-255, as well as any Unicode character as a numeric code, however, they cannot start with a dash or a digit.
#abc123 {color: red; background: black}
This and only this element can be identified as abc123
13. What is contextual selector?
Contextual selector is a selector that addresses specific occurrence of an element. It is a string of individual selectors separated by white space, a search pattern, where only the last element in the pattern is addressed providing it matches the specified context.
TD P CODE {color: red}
The element CODE will be displayed in red but only if it occurs in the context of the element P which must occur in the context of the element TD.
14. How do I have a background image that isn’t tiled?
Specify the background-repeat property as no-repeat. You can also use the background property as a shortcut for specifying multiple background-* properties at once. Here’s an example:
BODY {background: #fff url(watermark.jpg) no-repeat;}
15. What does \ABCD (and \ABCDE) mean?
CSS allows Unicode characters to be entered by number. For example, if a CLASS value in some Russian document contains Cyrillic letters EL PE (Unicode numbers 041B and 041F) and you want to write a style rule for that class, you can put that letter into the style sheet by writing:
.41B41F {font-style: italic;}
This works on all keyboards, so you don’t need a Cyrillic keyboard to write CLASS names in Russian or another language that uses that script.
The digits and letters after the backslash (\) are a hexadecimal number. Hexadecimal numbers are made from ordinary digits and the letters A to F (or a to f). Unicode numbers consist of four such digits.
If the number starts with a 0, you may omit it. The above could also be written as:
.\41B\41F {font-style: italic;}
But be careful if the next letter after the three digits is also a digit or a letter a to f! This is OK: .\41B-\41F, since the dash (-) cannot be mistaken for a hexadecimal digit, but .\41B9\41F is only two letters, not three.
Four digits is the maximum, however, so if you write:
.41B941F {font-style: italic;}
16. What are the advantages/disadvantages of the various style methods?
External Style Sheets
Advantages
* Can control styles for multiple documents at once
* Classes can be created for use on multiple HTML element types in many documents
* Selector and grouping methods can be used to apply styles under complex contexts
Disadvantages
* An extra download is required to import style information for each document
* The rendering of the document may be delayed until the external style sheet is loaded
* Becomes slightly unwieldy for small quantities of style definitions
Embedded Style Sheets
Advantages
* Classes can be created for use on multiple tag types in the document
* Selector and grouping methods can be used to apply styles under complex contexts
* No additional downloads necessary to receive style information
Disadvantages
* This method can not control styles for multiple documents at once
Inline Styles
Advantages
* Useful for small quantities of style definitions
* Can override other style specification methods at the local level so only exceptions need to be listed in conjunction with other style methods
Disadvantages
* Does not distance style information from content (a main goal of SGML/HTML)
* Can not control styles for multiple documents at once
* Author can not create or control classes of elements to control multiple element types within the document
* Selector grouping methods can not be used to create complex element addressing scenarios
17. What is inline style? How to link?
Inline style is the style attached to one specific element. The style is specified directly in the start tag as a value of the STYLE attribute and will apply exclusively to this specific element occurance.
18. What is imported Style Sheet? How to link?
Imported Style Sheet is a sheet that can be imported to (combined with) another sheet. This allows creating one main sheet containing declarations that apply to the whole site and partial sheets containing declarations that apply to specific elements (or documents) that may require additional styling. By importing partial sheets to the main sheet a number of sources can be combined into one.
To import a style sheet or style sheets include the @import notation or notations in the STYLE element. The @import notations must come before any other declaration. If more than one sheet is imported they will cascade in order they are imported – the last imported sheet will override the next last; the next last will override the second last, and so on. If the imported style is in conflict with the rules declared in the main sheet then it will be overridden.
.
19. What is alternate Style Sheet? How to link?
Alternate Style Sheet is a sheet defining an alternate style to be used in place of style(s) declared as persistent and/or preferred .
Persistent style is a default style that applies when style sheets are enabled but can disabled in favor of an alternate style, e.g.: <LINK REL=Stylesheet HREF=”style.css” TYPE=”text/css”>
Preferred style is a default style that applies automatically and is declared by setting the TITLE attribute to the LINK element. There can only be one preferred style, e.g.:  <LINK REL=Stylesheet HREF=”style2.css” TYPE=”text/css” TITLE=”appropriate style description”>
Alternate style gives an user the choice of selecting an alternative style – a very convenient way of specifying a media dependent style. Note: Each group of alternate styles must have unique TITLE, e.g.:
<LINK REL=”Alternate Stylesheet” HREF=”style3.css” TYPE=”text/css” TITLE=”appropriate style description” MEDIA=screen>
<LINK REL=”Alternate Stylesheet” HREF=”style4.css” TYPE=”text/css” TITLE=”appropriate style description” MEDIA=print>
20. How can you set a minimum width for IE?
To set a minimum width, the CSS property is ‘min-width’. This can be very useful and works well in good browsers. IE doesn’t understand ‘min-width’. However, it has a proprietary property called ‘expression’ which allows us to feed it javascript via a stylesheet. Below is how to set a (780px) minimum width for IE…

body {
width:expression(documentElement.clientWidth < 780 ? (documentElement.clientWidth == 0 ? (body.clientWidth < 780 ? “780px” : “auto”) : “780px”) : “auto” );
}
As the property is non-standard, it won’t validate with the W3C validator, so if we put it in the head like this (above) – in an IE conditional comment – the validator will ignore it and the page will get a clean bill of health.
21. How do I place text over an image?
To place text or image over an image you use the position property. The below exemple is supported by IE 4.0. All you have to do is adapt the units to your need.
“<div style=”position: relative; width: 200px; height: 100px”>
<div style=”position: absolute; top: 0; left: 0; width: 200px”>
<image>
</div>
<div style=”position: absolute; top: 20%; left: 20%; width: 200px”>
Text that nicely wraps
</div>
</div> ”
22. What is attribute selector?
Attribute selector is a selector defined by 1) the attribute set to element(s), 2) the attribute and value(s), 3) the attribute and value parts:
1a) A[title] {text-decoration: underline}
All A elements containing the TITLE attribute will be underlined
1b) A[class=name] {text-decoration: underline}
The A elements classed as ‘name’ will be underlined
2) A[title=”attribute element”] {text-decoration: underline}
The A elements containing the TITLE attribute with a value that is an exact match of the specified value, which in this example is ‘attribute element’, will be underlined
3) A[title~=”attribute”] {text-decoration: underline}
The A elements containing the TITLE attribute with a value containing the specified word, which in this example is ‘attribute’, will be underlined
23. What is parent-child selector?
Parent-child selector is a selector representing the direct descendent of a parent element. Parent-child selectors are created by listing two or more tilde (~) separated selectors.
“BODY ~ P {background: red; color: white}
The P element will be declared the specified style only if it directly descends from the BODY element:
<BODY> <P>Red and white paragraph </P> </BODY>
BODY ~ P ~ EM {background: red; color: white}
The EM element will be declared the specified style only if it directly descends from the P element which in its turn directly descends from the BODY element:
<P> <EM>Red and white EM </EM> </P> </BODY>”
24. What are inline, block, parent, children, replaced and floating elements?
Inline elements
which do not have line breaks. Can occur in block elements or other inline elements, cannot contain block elements.
Inline elements in HTML 3.2; EM, STRONG, DFN, CODE, SAMP, KBD, VAR, CITE, TT, I, B, U, STRIKE, BIG, SMALL, SUB, SUP, A, IMG, APPLET, FONT, BASEFONT, BR, SCRIPT, MAP, INPUT, SELECT, TEXTAREA.
Inline elements in HTML 4.0; EM, STRONG, DFN, CODE, SAMP, KBD, VAR, CITE, ABBR, ACRONYM, TT, I, B, BIG, SMALL, SUB, SUP, A, IMG, OBJECT, BR, SCRIPT, MAP, Q, SPAN, BDO, INPUT, SELECT, TEXTAREA, LABEL, BUTTON, (INS, DEL).
Inline elements in HTML 4.0 Transitional; EM, STRONG, DFN, CODE, SAMP, KBD, VAR, CITE, ABBR, ACRONYM, TT, I, B, U, S, STRIKE, BIG, SMALL, SUB, SUP, A, IMG, APPLET, OBJECT, FONT, BASEFONT, BR, SCRIPT, MAP, Q, SPAN, BDO, IFRAME, INPUT, SELECT, TEXTAREA, LABEL, BUTTON, (INS, DEL).
Block elements
which do have line breaks. May occur in other block elements, cannot occur in inline elements, may contain both block and inline elements.
Block elements in HTML 3.2; H1, H2, H3, H4, H5, H6, ADDRESS, P, DL, DT, DD, UL, OL, DIR, MENU, LI, DIV, CENTER, BLOCKQUOTE, PRE, HR, ISINDEX, TABLE, FORM.
Block elements in HTML 4.0; P, H1, H2, H3, H4, H5, H6, UL, OL, PRE, DL, DIV, NOSCRIPT, BLOCKQUOTE, FORM, HR, TABLE, FIELDSET, ADDRESS, (INS, DEL).
Block elements in HTML 4.0 Transitional; P, H1, H2, H3, H4, H5, H6, UL, OL, DIR, MENU, PRE, DL, DIV, CENTER, NOSCRIPT, NOFRAMES, BLOCKQUOTE, FORM, ISINDEX, HR, TABLE, FIELDSET, ADDRESS, (INS, DEL).
Parents and children elements
which either contain (parents) or are in the content of (children) other elements, e.g.
” e.g. <P>text<STRONG>text</STRONG>text</P>.”  P is a parent of STRONG. STRONG is a child of P. If not specified otherwise, children will inherit parent’s properties.
Replaced
elements which content is replaced. For example content of the IMG element is replaced with an image, content of the INPUT element is replace with a field.
Floating
elements which follow the flow of a parent – inline elements.
25. What are pseudo-classes?
Pseudo-classes are fictional element types that do not exist in HTML. In CSS1 there is only one element type which can be classed this way, namely the A element (anchor). By creating three fictional types of the A element individual style can be attached to each class. These three fictional element types are: A as unvisited link, A as active link and A as visited link. Pseudo-classes are created by a colon followed by pseudo-class’s name. They can also be combined with normal classes, e.g.:
A:link {background: black; color: white}
A:active {background: black; color: red}
A:visited {background: transparent; color: black}
This anchor (or rather these anchors) will be displayed as declared above
A.foot:link {background: black; color: white}
A.foft:active {background; black: color: red}
A.foot:visited {background: transparent; color: black}
This anchor and all other anchors with CLASS foot will be displayed as declared above
26. What is CSS rule ‘at-rule’?
There are two types of CSS rules: ruleset and at-rule. At-rule is a rule that applies to the whole style sheet and not to a specific selector only (like in ruleset). They all begin with the @ symbol followed by a keyword made up of letters a-z, A-Z, digits 0-9, dashes and escaped characters, e.g. @import or @font-face.
27. What is ‘important’ declaration?
Important declaration is a declaration with increased weight. Declaration with increased weight will override declarations with normal weight. If both reader’s and author’s style sheet contain statements with important declarations the author’s declaration will override the reader’s.
BODY {background: white ! important; color: black}
In the example above the background property has increased weight while the color property has normal.
27 To what are partial URLs relative?
Partial URLs are relative to the source of the style sheet. The style sheet source can either be linked or embedded. To which source partial URLs are relative to depends on their occurrence.
If a partial URL occurs in a linked style sheet then it is relative to the linked style sheet. The URL of the linked style sheet is the URL of the directory where the sheet is kept.
If a partial URL occurs in an embedded style sheet then it is relative to the embedded style sheet. The URL of the embedded style sheet is the URL of the HTML document in which the sheet is embedded.
Note that Navigator 4.x treats partial URLs as being relative to the HTML document, regardless of the place where the partial URL occurs. This is a serious bug which forces most authors to use absolute URLs in their CSS.
28 What is the difference between ID and CLASS?
ID identifies and sets style to one and only one occurrence of an element while class can be attached to any number of elements. By singling out one occurrence of an element the unique value can be declared to said element.
CSS
#eva1 {background: red; color: white}
.eva2 {background: red; color: white}
“HTML – ID
<P ID=eva1>Paragraph 1 – ONLY THIS occurrence of the element P (or single occurrence of some other element) can be identified as eva1</P>
<P ID=eva1>Paragraph 2 – This occurrence of the element P CANNOT be identified as eva1</P>
HTML – CLASS
<P class=eva2>Paragraph 1 – This occurrence of the element P can be classified as eva2</P>
<P class=eva2>Paragraph 2 – And so can this, as well as occurrences of any other element, </P> ”
29. What is shorthand property?
Shorthand property is a property made up of individual properties that have a common “addressee”. For example properties: font-weight, font-style, font-variant, font-size, font-family, refer to the font. To reduce the size of style sheets and also save some keystrokes as well as bandwidth they can all be specified as one shorthand property font, e.g.:
H1 {font-weight: bold;
font-style: italic;
font-variant: small-caps;
font-size: 160%;
font-family: serif}
can be all shorthanded to a space separated list:
H1 {font: bold italic small-caps 160% serif}
Note: To make things even simpler the line-height property can be specified together with the font-size property:
H1 {font: bold italic small-caps 160%/170% serif}
30. How does inheritance work?
HTML documents are structured hierarchically. There is an ancestor, the top level element, the HTML element, from which all other elements (children) are descended. As in any other family also children of the HTML family can inherit their parents, e.g. color or size.
By letting the children inherit their parents a default style can be created for top level elements and their children. (Note: not all properties can be inherited). The inheritance starts at the oldest ancestor and is passed on to its children and then their children and the children’s children and so on.
Inherited style can be overridden by declaring specific style to child element. For example if the EM element is not to inherit its parent P then own style must be declared to it. For example:
BODY {font-size: 10pt}
All text will be displayed in a 10 point font
BODY {font-size: 10pt}
H1 {font-size: 14pt} or H1 {font-size: 180%}
All text except for the level 1 headings will be displayed in a 10 point font. H1 will be displayed in a 14 point font (or in a font that is 80% larger than the one set to BODY). If the element H1 contains other elements, e.g. EM then the EM element will also be displayed in a 14 point font (or 180%) it will inherit the property of the parent H1. If the EM element is to be displayed in some other font then own font properties must be declared to it, e.g:
BODY {font-size: 10pt}
H1 {font-size: 14pt} or H1 {font-size: 180%}
EM {font-size: 15pt} or EM {font-size: 110%}
The EM element will be displayed in a 15 point font or will be 10% larger than H1. NOTE: EM is, in this example, inside H1 therefore will inherit H1’s properties and not BODY’s.
The above declaration will display all EM elements in 15 point font or font that is 10% larger than font declared to the parent element. If this specific font is to apply to EM elements but only if they are inside H1 and not every occurrence of EM then EM must take a form of a contextual selector.
H1 EM {font-size: 15pt} or H1 EM {font-size: 110%}
In the example above EM is a contextual selector. It will be displayed in specified font only if it will be found in the context of H1.
Not all properties are inherited. One such property is background. However, since it’s initial value is transparent the background of the parent element will shine through by default unless it is explicitly set.
31. What is Extensible Stylesheet Language (XSL)?
XSL is a proposed styling language for formatting XML (eXtensible Markup Language) documents. The proposal was submitted to the W3C by Microsoft, Inso, and ArborText.
32. How do you make a tooltip that appears on hover?
The most simple way is to use the ‘title’ attribute like this…
“HTML
<span title=”Example of the title attribute in use”>like this</span>
CSS
a.tooltip {
position:relative;
cursor:help;
}
a.tooltip span {
display:none;
position:absolute;
top:1.5em;
left:0;
width:15em;
padding:0 2px;
}
a.tooltip:hover {
display:inline;
}
a.tooltip:hover span {
display:block;
border:1px solid gray;
background-color:white;
}
HTML
<a class=”tooltip” href=”#n”>Karl Marx<span>-info goes here-</span></a>
Without this part… a.tooltip:hover {
display:inline;
}
..it won’t work in IE.
The “#n” in the link is to prevent the page from jumping to the top if the link is clicked. The “href” part is necessary as it won’t work in IE without it.”
var gaJsHost = ((“https:” == document.location.protocol) ? “https://ssl.” : “http://www.”);
document.write(unescape(“%3Cscript src='” + gaJsHost + “google-analytics.com/ga.js’ type=’text/javascript’%3E%3C/script%3E”));
try {
var pageTracker = _gat._getTracker(“UA-1855756-5”);
pageTracker._trackPageview();
} catch(err) {}

Categories
MySQL PHP

PHP interview questions & ANSWERS

Q:1 What are the differences between Get and post methods in form submitting.
give the case where we can use get and we can use post methods?
A:1
When to use GET or  POST

The HTML 2.0 specification says, in section Form
Submission (and the HTML 4.0 specification repeats this with minor
stylistic changes):

–>If the processing of a form is idempotent
(i.e. it has no lasting observable effect on the state of the
world), then the form method should be GET. Many database searches
have no visible side-effects and make ideal applications of query
forms.

–>If the service associated with the processing of a form has side
effects (for example, modification of a database or subscription to
a service), the method should be POST.
How the form data is transmitted?

quotation from the HTML 4.0 specification

–> If the method is “get” – -, the user agent
takes the value of action, appends a ? to it, then appends the form
data set, encoded using the application/x-www-form-urlencoded
content type. The user agent then traverses the link to this URI. In
this scenario, form data are restricted to ASCII codes.
–> If the method is “post” –, the user agent conducts an HTTP post
transaction using the value of the action attribute and a message
created according to the content type specified by the enctype
attribute.
Quote from CGI FAQ

Firstly, the the HTTP protocol specifies
differing usages for the two methods. GET requests should always be
idempotent on the server. This means that whereas one GET request
might (rarely) change some state on the Server, two or more
identical requests will have no further effect.

This is a theoretical point which is also good
advice in practice. If a user hits “reload” on his/her browser, an
identical request will be sent to the server, potentially resulting
in two identical database or
guestbook entries, counter increments, etc. Browsers may reload a
GET URL automatically, particularly if cacheing is disabled (as is
usually the case with CGI output), but will typically prompt the
user before
re-submitting a POST request. This means you’re far less likely to
get inadvertently-repeated entries from POST.

GET is (in theory) the preferred method for
idempotent operations, such as querying a database, though it
matters little if you’re using a form. There is a further practical
constraint that many systems have built-in limits to the length of a
GET request they can handle: when the total size of a request (URL+params)
approaches or exceeds 1Kb, you are well-advised to use POST in any
case.

I would prefer POST when I don’t want the status to
be change when user resubmits. And GET
when it does not matter.

Q:2 Who is the father of PHP and explain the changes in PHP versions?
A:2 Rasmus Lerdorf is known as the father of PHP.PHP/FI 2.0 is an early and no longer supported version of PHP. PHP 3
is the successor to PHP/FI 2.0 and is a lot nicer. PHP 4 is the current
generation of PHP, which uses the
Zend engine
under the
hood. PHP 5 uses
Zend engine 2 which,
among other things, offers many additionalOOP features

Q:3 How can we submit a form without a submit button?
A:3 The main idea behind this is to use Java script submit() function in
order to submit the form without explicitly clicking any submit button.
You can attach the document.formname.submit() method to onclick,
onchange events of different inputs and perform the form submission. you
can even built a timer function where you can automatically submit the
form after xx seconds once the loading is done (can be seen in online
test sites).

Q:4 In how many ways we can retrieve the data in the result set of
MySQL using PHP?

A:4 You can do it by 4 Ways1. mysql_fetch_row.
2. mysql_fetch_array
3. mysql_fetch_object
4. mysql_fetch_assoc

Q:5 What is the difference between mysql_fetch_object and
mysql_fetch_array?

A:5 mysql_fetch_object() is similar tomysql_fetch_array(), with one difference –
an object is returned, instead of an array. Indirectly, that means that
you can only access the data by the field names, and not by their
offsets (numbers are illegal property names).

Q:6 What is the difference between $message and $$message?
A:6 It is a classic example of PHP’s variable variables. take the
following example.$message = “Mizan”;$$message = “is a moderator of PHPXperts.”;$message is a simple PHP variable that we are used to. But the
$$message is not a very familiar face. It creates a variable name $mizan
with the value “is a moderator of PHPXperts.” assigned. break it like
this${$message} => $mizanSometimes it is convenient to be able to have variable variable
names. That is, a variable name which can be set and used dynamically.

Q:7 How can we extract string ‘abc.com ‘ from a string ‘http://info@abc.com’
using regular expression of PHP?

A:7 preg_match(”/^http:\/\/.+@(.+)$/”,’http://info@abc.com’,$found);
echo $found[1];

Q:8 How can we create a database using PHP and MySQL?
A:8 We can create MySQL database with the use of
mysql_create_db(“Database Name”)

Q:9 What are the differences between require and include,
include_once and require_once?
A:9

The include() statement includes
and evaluates the specified file.The documentation below also applies to
require(). The two constructs
are identical in every way except how they handle
failure. include() produces a
Warning while require() results
in a Fatal Error. In other words, use
require() if you want a missing
file to halt processing of the page.
include() does not behave this way, the script will
continue regardless.

The include_once()
statement includes and evaluates the
specified file during the execution of
the script. This is a behavior similar
to the include()
statement, with the only difference
being that if the code from a file has
already been included, it will not be
included again. As the name suggests, it
will be included just once.include_once()
should be used in cases where the same
file might be included and evaluated
more than once during a particular
execution of a script, and you want to
be sure that it is included exactly once
to avoid problems with function
redefinitions, variable value
reassignments, etc.

require_once()
should be used in cases where the same
file might be included and evaluated
more than once during a particular
execution of a script, and you want to
be sure that it is included exactly once
to avoid problems with function
redefinitions, variable value
reassignments, etc.

Q:10 Can we use include (”abc.PHP”) two times in a PHP page “makeit.PHP”?
A:10 Yes we can use include() more than one time in any page though it is
not a very good practice.

Q:11 What are the different tables present in MySQL, which type of
table is generated when we are creating a table in the following syntax:
create table employee (eno int(2),ename varchar(10)) ?

A:11 Total 5 types of tables we can create
1. MyISAM
2. Heap
3. Merge
4. INNO DB
5. ISAM
MyISAM is the default storage engine as of MySQL 3.23 and as a result if
we do not specify the table name explicitly it will be assigned to the
default engine.

Q:12 Functions in IMAP, POP3 AND LDAP?
A:12 These functions enable you to operate with the IMAP protocol, as well as the NNTPPOP3 and local mailbox access methods  You can find these specific information in PHP Manual.

Q:13 How can I execute a PHP script using command line?
A:13 As of version 4.3.0, PHP supports a new SAPI type (Server
Application Programming Interface) named CLI which means Command Line
Interface. Just run the PHP CLI (Command Line Interface) program and
provide the PHP script file name as the command line argument. For
example, “php myScript.php”, assuming “php” is the command to invoke the
CLI program.
Be aware that if your PHP script was written for the Web CGI interface,
it may not execute properly in command line environment.

Q:14 Suppose your Zend engine supports the mode Then how can u
configure your PHP Zend engine to support mode ?

A:14 In php.ini file:
set
short_open_tag=on
to make PHP support

Q:15 Shopping cart online validation i.e. how can we configure Paypal,
etc.?

A:15 We can find the detail documentation about different paypal
integration process at the following site

PayPal PHP
SDK : http://www.paypaldev.org

Q:16 What is meant by nl2br()?
A:16 Inserts HTML line breaks (
) before all newlines in a string
string nl2br (string); Returns string with ” inserted before all
newlines. For example: echo nl2br(”god bless\n you”) will output “god
bless
you” to your browser.

Q:17 Draw the architecture of Zend engine?
A:17 The Zend Engine is the internal compiler and runtime engine used by
PHP4. Developed by Zeev Suraski and Andi Gutmans, the Zend Engine is an
abbreviation of their names. In the early days of PHP4, it worked as
follows:
The PHP script was loaded by the Zend Engine and compiled into Zend
opcode. Opcodes, short for operation codes, are low level binary
instructions. Then the opcode was executed and the HTML generated sent
to the client. The opcode was flushed from memory after execution.Today, there are a multitude of products and techniques to help you
speed up this process. In the following diagram, we show the how modern
PHP scripts work; all the shaded boxes are optional.
PHP Scripts are loaded into memory and compiled into Zend opcodes.

Q:18 What are the current versions of apache, PHP, and MySQL?
A:18 As of February, 2007 the current versions arePHP: php5.2.1
MySQL: MySQL 5.2
Apache: Apache 2.2.4Note: visit www.php.net,

http://dev.mysql.com/downloads/mysql/,
www.apache.org to get current
versions.

Q:19 What are the reasons for selecting lamp (Linux, apache, MySQL,
PHP) instead of combination of other software programs, servers and
operating systems?

A:19 All of those are open source resource. Security of Linux is very
very more than windows. Apache is a better server that IIS both in
functionality and security. MySQL is world most popular open source
database. PHP is more faster that asp or any other scripting language.

Q:20 How can we encrypt and decrypt a data present in a MySQL table
using MySQL?

A:20 AES_ENCRYPT () and AES_DECRYPT ()

Q:21 How can we encrypt the username and password using PHP?
A:21 The functions in this section perform encryption and decryption, and
compression and uncompression:

encryption decryption
AES_ENCRYT() AES_DECRYPT()
ENCODE() DECODE()
DES_ENCRYPT() DES_DECRYPT()
ENCRYPT() Not available
MD5() Not available
OLD_PASSWORD() Not available
PASSWORD() Not available
SHA() or SHA1() Not available
Not available UNCOMPRESSED_LENGTH()

Q:22 What are the features and advantages of object-oriented
programming?

A:22 One of the main advantages of OO programming is its ease of
modification; objects can easily be modified and added to a system there
by reducing maintenance costs. OO programming is also considered to be
better at modeling the real world than is procedural programming. It
allows for more complicated and flexible interactions. OO systems are
also easier for non-technical personnel to understand and easier for
them to participate in the maintenance and enhancement of a system
because it appeals to natural human cognition patterns.
For some systems, an OO approach can speed development time since many
objects are standard across systems and can be reused. Components that
manage dates, shipping, shopping carts, etc. can be purchased and easily
modified for a specific system

Q:23 What are the differences between procedure-oriented languages and
object-oriented languages?

A:23 Traditional programming has the following characteristics:Functions are written sequentially, so that a change in programming can
affect any code that follows it.
If a function is used multiple times in a system (i.e., a piece of code
that manages the date), it is often simply cut and pasted into each
program (i.e., a change log, order function, fulfillment system, etc).
If a date change is needed (i.e., Y2K when the code needed to be changed
to handle four numerical digits instead of two), all these pieces of
code must be found, modified, and tested.
Code (sequences of computer instructions) and data (information on which
the instructions operates on) are kept separate. Multiple sets of code
can access and modify one set of data. One set of code may rely on data
in multiple places. Multiple sets of code and data are required to work
together. Changes made to any of the code sets and data sets can cause
problems through out the system.Object-Oriented programming takes a radically different approach:Code and data are merged into one indivisible item – an object (the
term “component” has also been used to describe an object.) An object is
an abstraction of a set of real-world things (for example, an object may
be created around “date”) The object would contain all information and
functionality for that thing (A date
object it may contain labels like January, February, Tuesday, Wednesday.
It may contain functionality that manages leap years, determines if it
is a business day or a holiday, etc., See Fig. 1). Ideally, information
about a particular thing should reside in only one place in a system.
The information within an object is encapsulated (or hidden) from the
rest of the system.
A system is composed of multiple objects (i.e., date function, reports,
order processing, etc., See Fig 2). When one object needs information
from another object, a request is sent asking for specific information.
(for example, a report object may need to know what today’s date is and
will send a request to the date object) These requests are called
messages and each object has an interface that manages messages.
OO programming languages include features such as “class”, “instance”,
“inheritance”, and “polymorphism” that increase the power and
flexibility of an object.

Q:24 What is the use of friend function?
A:24 Sometimes a function is best shared among a number of different
classes. Such functions can be declared either as member functions of
one class or as global functions. In either case they can be set to be
friends of other classes, by using a friend specifier in the class that
is admitting them. Such functions can use all attributes of the class
which names them as a friend, as if they were themselves members of that
class.
A friend declaration is essentially a prototype for a member function,
but instead of requiring an implementation with the name of that class
attached by the double colon syntax, a global function or member
function of another class provides the match.

Q:25 What are the differences between public, private, protected,
static, transient, final and volatile?

A:25 Public: Public declared items can be accessed everywhere.
Protected: Protected limits access to inherited and parent
classes (and to the class that defines the item).
Private: Private limits visibility only to the class that defines
the item.
Static: A static variable exists only in a local function scope,
but it does not lose its value when program execution leaves this scope.
Final: Final keyword prevents child classes from overriding a
method by prefixing the definition with final. If the class itself is
being defined final then it cannot be extended.
transient: A transient variable is a variable that may not
be serialized.
volatile: a variable that might be concurrently modified by multiple
threads should be declared volatile. Variables declared to be volatile
will not be optimized by the compiler because their value can change at
any time.

Q:26 What are the different types of errors in PHP?
A:26 Three are three types of errors:1. Notices: These are trivial,
non-critical errors that PHP encounters while executing a script – for
example, accessing a variable that has not yet been defined. By default,
such errors are not displayed to the user at all – although, as you will
see, you can change this default behavior.2. Warnings: These are more serious errors – for example, attempting
to include() a file which does not exist. By default, these errors are
displayed to the user, but they do not result in script termination.3. Fatal errors: These are critical errors – for example,
instantiating an object of a non-existent class, or calling a
non-existent function. These errors cause the immediate termination of
the script, and PHP’s default behavior is to display them to the user
when they take place.

Q:27 What is the functionality of the function strstr and stristr?
A:27 strstr:

Returns part of haystack
string from the first occurrence of
needle to the end of
haystack.If needle is not found,
returns FALSE.

If needle is not a
string, it is converted to an integer and applied as the
ordinal value of a character.

This function is case-sensitive. For
case-insensitive searches, use
stristr().

Q:28 What are the differences between PHP 3 and PHP 4 and PHP 5?
A:28 Please read the release notes at
http://www.php.net.

Q:29 How can we convert asp pages to PHP pages?
A:29 there are lots of tools available for asp to PHP conversion. you can
search Google for that. the best one is available athttp://asp2php.naken.cc./

Q:30 What is the functionality of the function htmlentities?
A:30 Convert all applicable characters to HTML entities
This function is identical to htmlspecialchars() in all ways, except
with htmlentities(), all characters which have HTML character entity
equivalents are translated into these entities.

Q:31 How can we get second of the current time using date function?
A:31 $second = date(”s”);

Q:32 How can we convert the time zones using PHP?
A:32 By using date_default_timezone_get and
date_default_timezone_set function on PHP 5.1.0

// Discover what 8am in Tokyo relates to on the East Coast of the US

// Set the default timezone to Tokyo time:
date_default_timezone_set(‘Asia/Tokyo’);

// Now generate the timestamp for that particular timezone, on Jan 1st, 2000
$stamp = mktime(8, 0, 0, 1, 1, 2000);

// Now set the timezone back to US/Eastern
date_default_timezone_set(‘US/Eastern’);

// Output the date in a standard format (RFC1123), this will print:
// Fri, 31 Dec 1999 18:00:00 EST
echo ‘

‘, date(DATE_RFC1123, $stamp) ,’

‘;?>

Q:33 What is meant by urlencode and urldecode?
A:33 URLencode returns a string in which all non-alphanumeric characters
except -_. have been replaced with a percent (%)
sign followed by two hex digits and spaces encoded as plus (+)
signs. It is encoded the same way that the posted data from a WWW form
is encoded, that is the same way as in
application/x-www-form-urlencoded media type.

urldecode decodes any %##
encoding in the given string.

Q:34 What is the difference between the functions unlink and unset?
A:34 unlink() deletes the given file from the file system.
unset() makes a variable undefined.

Q:35 How can we register the variables into a session?
A:35 $_SESSION[’name’] = “Mizan”;

Q:36 How can we get the properties (size, type, width, height) of an
image using PHP image functions?

A:36 To know the Image type use exif_imagetype () function
To know the Image size use getimagesize () function
To know the image width use imagesx () function
To know the image height use imagesy() function t

Q:37 How can we get the browser properties using PHP?
A:37 By using
$_SERVER[‘HTTP_USER_AGENT’]
variable.

Q:38 What is the maximum size of a file that can be uploaded using PHP
and how can we change this?

A:38 By default the maximum size is 2MB. and we can change the following
setup at php.iniupload_max_filesize = 2M

Q:39 How can we increase the execution time of a PHP script?
A:39 by changing the following setup at php.inimax_execution_time = 30
; Maximum execution time of each script, in seconds

Q:40 How can we take a backup of a MySQL table and how can we restore
it. ?

A:40 To backup: BACKUP TABLE tbl_name[,tbl_name…] TO
‘/path/to/backup/directory’
RESTORE TABLE tbl_name[,tbl_name…] FROM ‘/path/to/backup/directory’mysqldump: Dumping Table Structure and DataUtility to dump a database or a collection of database for backup or
for transferring the data to another SQL server (not necessarily a MySQL
server). The dump will contain SQL statements to create the table and/or
populate the table.
-t, –no-create-info
Don’t write table creation information (the CREATE TABLE statement).
-d, –no-data
Don’t write any row information for the table. This is very useful if
you just want to get a dump of the structure for a table!

Q:41 How can we optimize or increase the speed of a MySQL select
query?

A:41

* first of all instead of using select * from table1, use select
column1, column2, column3.. from table1
* Look for the opportunity to introduce index in the table you are
querying.
* use limit keyword if you are looking for any specific number of
rows from the result set.

Q:42 How many ways can we get the value of current session id?
A:42 session_id() returns the session id for the current session.

Q:43 How can we destroy the session, how can we unset the variable of
a session?

A:43 session_unregister — Unregister a global variable from the current
session
session_unset — Free all session variables

Q:44 How can we destroy the cookie?
A:44 Set the cookie in past.

Q:45 How many ways we can pass the variable through the navigation
between the pages?

A:45

* GET/QueryString
* POST

Q:46 What is the difference between ereg_replace() and eregi_replace()?
A:46 eregi_replace() function is identical to ereg_replace() except that
this ignores case distinction when matching alphabetic
characters.eregi_replace() function is identical to ereg_replace()
except that this ignores case distinction when matching alphabetic
characters.

Q:47 What are the different functions in sorting an array?
A:47 Sort(), arsort(),
asort(), ksort(),
natsort(), natcasesort(),
rsort(), usort(),
array_multisort(), and
uksort().

Q:48 How can we know the count/number of elements of an array?
A:48 2 ways
a) sizeof($urarray) This function is an alias of count()
b) count($urarray)

Q:49 What is the PHP predefined variable that tells the What types of
images that PHP supports?

A:49 Though i am not sure if this is wrong or not, With the exif
extension you are able to work with image meta data.

Q:50 How can I know that a variable is a number or not using a
JavaScript?

A:50 bool is_numeric ( mixed var)
Returns TRUE if var is a number or a numeric string, FALSE otherwise.or use isNaN(mixed var)The isNaN() function is used to check if a value is not a number.

Q:51 List out some tools through which we can draw E-R diagrams for
mysql.

A:51 Case Studio
Smart Draw

Q:52 How can I retrieve values from one database server and store them
in other database server using PHP?

A:52 we can always fetch from one database and rewrite to another. here
is a nice solution of it.$db1 = mysql_connect(”host”,”user”,”pwd”)
mysql_select_db(”db1″, $db1);
$res1 = mysql_query(”query”,$db1);$db2 = mysql_connect(”host”,”user”,”pwd”)
mysql_select_db(”db2″, $db2);
$res2 = mysql_query(”query”,$db2);At this point you can only fetch records from you previous ResultSet,
i.e $res1 – But you cannot execute new query in $db1, even if you
supply the link as because the link was overwritten by the new db.so at this point the following script will fail
$res3 = mysql_query(”query”,$db1); //this will failSo how to solve that?

take a look below.
$db1 = mysql_connect(”host”,”user”,”pwd”)
mysql_select_db(”db1″, $db1);
$res1 = mysql_query(”query”,$db1);

$db2 = mysql_connect(”host”,”user”,”pwd”, true)
mysql_select_db(”db2″, $db2);
$res2 = mysql_query(”query”,$db2);

So mysql_connect has another optional boolean parameter which
indicates whether a link will be created or not. as we connect to the
$db2 with this optional parameter set to ‘true’, so both link will
remain live.

now the following query will execute successfully.
$res3 = mysql_query(”query”,$db1);

Thanks goes to Hasan and Hasin for this solution.

Q:53 List out the predefined classes in PHP?
A:53 Directory
stdClass
__PHP_Incomplete_Class
exception
php_user_filter

Q:54 How can I make a script that can be bi-language (supports
English, German)?

A:54 You can maintain two separate language file for each of the
language. all the labels are putted in both language files as variables
and assign those variables in the PHP source. on runtime choose the
required language option.

Q:55 What are the difference between abstract class and interface?
A:55 Abstract class: abstract classes are the class where one or more
methods are abstract but not necessarily all method has to be abstract.
Abstract methods are the methods, which are declare in its class but not
define. The definition of those methods must be in its extending class.Interface: Interfaces are one type of class where all the methods are
abstract. That means all the methods only declared but not defined. All
the methods must be define by its implemented class.

Q:56 How can we send mail using JavaScript?
A:56 JavaScript does not have any networking capabilities as it is
designed to work on client site. As a result we can not send mails using
JavaScript. But we can call the client side mail protocol mailto
via JavaScript to prompt for an email to send. this requires the client
to approve it.

Q:57 How can we repair a MySQL table?
A:57 The syntex for repairing a MySQL table is
REPAIR TABLENAME, [TABLENAME, ], [Quick],[Extended]
This command will repair the table specified if the quick is given the
MySQL will do a repair of only the index tree if the extended is given
it will create index row by row

Q:58 What are the advantages of stored procedures, triggers, indexes?
A:58 A stored procedure is a set of SQL commands that can be compiled and
stored in the server. Once this has been done, clients don’t need to
keep re-issuing the entire query but can refer to the stored procedure.
This provides better overall performance because the query has to be
parsed only once, and less information needs to be sent between the
server and the client. You can also raise the conceptual level by having
libraries of functions in the server. However, stored procedures of
course do increase the load on the database server system, as more of
the work is done on the server side and less on the client (application)
side.Triggers will also be implemented. A trigger is effectively a type of
stored procedure, one that is invoked when a particular event occurs.
For example, you can install a stored procedure that is triggered each
time a record is deleted from a transaction table and that stored
procedure automatically deletes the corresponding customer from a
customer table when all his transactions are deleted.Indexes are used to find rows with specific column values quickly.
Without an index, MySQL must begin with the first row and then read
through the entire table to find the relevant rows. The larger the
table, the more this costs. If the table has an index for the columns in
question, MySQL can quickly determine the position to seek to in the
middle of the data file without having to look at all the data. If a
table has 1,000 rows, this is at least 100 times faster than reading
sequentially. If you need to access most of the rows, it is faster to
read sequentially, because this minimizes disk seeks.

Q:59 What is the maximum length of a table name, database name, and
fieldname in MySQL?

A:59 The following table describes the maximum length for each type of
identifier.

Identifier Maximum Length
(bytes)
Database 64
Table 64
Column 64
Index 64
Alias 255

There are some restrictions on the characters that may appear in
identifiers:

Q:60 How many values can the SET function of MySQL take?
A:60 MySQL set can take zero or more values but at the maximum it can
take 64 values

Q:61 What are the other commands to know the structure of table using
MySQL commands except explain command?

A:61 describe Table-Name;

Q:62 How many tables will create when we create table, what are they?
A:62 The ‘.frm’ file stores the table definition.
The data file has a ‘.MYD’ (MYData) extension.
The index file has a ‘.MYI’ (MYIndex) extension,

Q:63 What is the purpose of the following files having extensions 1) .frm
2) .myd 3) .myi? What do these files contain?

A:63 In MySql, the default table type is MyISAM.
Each MyISAM table is stored on disk in three files. The files have names
that begin with the table name and have an extension to indicate the
file type.
The ‘.frm’ file stores the table definition.
The data file has a ‘.MYD’ (MYData) extension.
The index file has a ‘.MYI’ (MYIndex) extension,

Q:64 What is maximum size of a database in MySQL?
A:64 If the operating system or filesystem places a limit on the number
of files in a directory, MySQL is bound by that constraint.The efficiency of the operating system in handling large numbers of
files in a directory can place a practical limit on the number of tables
in a database. If the time required to open a file in the directory
increases significantly as the number of files increases, database
performance can be adversely affected.
The amount of available disk space limits the number of tables.
MySQL 3.22 had a 4GB (4 gigabyte) limit on table size. With the MyISAM
storage engine in MySQL 3.23, the maximum table size was increased to
65536 terabytes (2567 – 1 bytes). With this larger allowed table size,
the maximum effective table size for MySQL databases is usually
determined by operating system constraints on file sizes, not by MySQL
internal limits.The InnoDB storage engine maintains InnoDB tables within a tablespace
that can be created from several files. This allows a table to exceed
the maximum individual file size. The tablespace can include raw disk
partitions, which allows extremely large tables. The maximum tablespace
size is 64TB.
The following table lists some examples of operating system file-size
limits. This is only a rough guide and is not intended to be definitive.
For the most up-to-date information, be sure to check the documentation
specific to your operating system.
Operating System File-size LimitLinux 2.2-Intel 32-bit 2GB (LFS: 4GB)
Linux 2.4+ (using ext3 filesystem) 4TB
Solaris 9/10 16TB
NetWare w/NSS filesystem 8TB
Win32 w/ FAT/FAT32 2GB/4GB
Win32 w/ NTFS 2TB (possibly larger)
MacOS X w/ HFS+ 2TB

Q:65 Give the syntax of Grant and Revoke commands?
A:65 The generic syntax for grant is as following
> GRANT [rights] on [database/s] TO [username@hostname] IDENTIFIED BY
[password]
now rights can be
a) All privileges
b) combination of create, drop, select, insert, update and delete etc.We can grant rights on all databse by using *.* or some specific
database by database.* or a specific table by database.table_name
username@hotsname can be either username@localhost, username@hostname
and username@%
where hostname is any valid hostname and % represents any name, the *.*
any condition
password is simply the password of userThe generic syntax for revoke is as following
> REVOKE [rights] on [database/s] FROM [username@hostname]
now rights can be as explained above
a) All privileges
b) combination of create, drop, select, insert, update and delete etc.
username@hotsname can be either username@localhost, username@hostname
and username@%
where hostname is any valid hostname and % represents any name, the *.*
any condition

Q:66 Explain Normalization concept?
A:66 The normalization process involves getting our data to conform to
three progressive normal forms, and a higher level of normalization
cannot be achieved until the previous levels have been achieved (there
are actually five normal forms, but the last two are mainly academic and
will not be discussed).First Normal FormThe First Normal Form (or 1NF) involves removal of redundant data
from horizontal rows. We want to ensure that there is no duplication of
data in a given row, and that every column stores the least amount of
information possible (making the field atomic).Second Normal FormWhere the First Normal Form deals with redundancy of data across a
horizontal row, Second Normal Form (or 2NF) deals with redundancy of
data in vertical columns. As stated earlier, the normal forms are
progressive, so to achieve Second Normal Form, your tables must already
be in First Normal Form.Third Normal Form

I have a confession to make; I do not often use Third Normal Form. In
Third Normal Form we are looking for data in our tables that is not
fully dependant on the primary key, but dependant on another value in
the table

Q:67 How can we find the number of rows in a table using MySQL?
A:67 Use this for mysql
>SELECT COUNT(*) FROM table_name;

Q:68 How can we find the number of rows in a result set using PHP?
A:68 $result = mysql_query($sql, $db_link);
$num_rows = mysql_num_rows($result);
echo “$num_rows rows found”;

Q:69 How many ways we can we find the current date using MySQL?
A:69 SELECT CURDATE();
CURRENT_DATE() = CURDATE()
for time use
SELECT CURTIME();
CURRENT_TIME() = CURTIME()

Q:70 What are the advantages and disadvantages of Cascading Style
Sheets?

A:70 External Style SheetsAdvantagesCan control styles for multiple documents at once. Classes can be
created for use on multiple HTML element types in many documents.
Selector and grouping methods can be used to apply styles under complex
contextsDisadvantagesAn extra download is required to import style information for each
document The rendering of the document may be delayed until the external
style sheet is loaded Becomes slightly unwieldy for small quantities of
style definitionsEmbedded Style Sheets

Advantages

Classes can be created for use on multiple tag types in the document.
Selector and grouping methods can be used to apply styles under complex
contexts. No additional downloads necessary to receive style information

Disadvantages

This method can not control styles for multiple documents at once

Inline Styles

Advantages

Useful for small quantities of style definitions. Can override other
style specification methods at the local level so only exceptions need
to be listed in conjunction with other style methods

Disadvantages

Does not distance style information from content (a main goal of
SGML/HTML). Can not control styles for multiple documents at once.
Author can not create or control classes of elements to control multiple
element types within the document. Selector grouping methods can not be
used to create complex element addressing scenarios

Q:71 What type of inheritance that PHP supports?
A:71 In PHP an extended class is always dependent on a single base class,
that is, multiple inheritance is not supported. Classes are extended
using the keyword ‘extends’.

Q:72 What is the difference between Primary Key and
Unique key?

A:72 Primary Key: A column in a table whose values uniquely identify the
rows in the table. A primary key value cannot be NULL.

Unique Key: Unique Keys are used to uniquely identify each row in the
table. There can be one and only one row for each unique key value. So
NULL can be a unique key.There can be only one primary key for a table but there can be more
than one unique for a table.

Q:73 The structure of table view buyers is as follows:

Field Type Null Key Default Extra
user_pri_id int(15) PRI null auto_increment
userid varchar(10) YES null

the value of user_pri_id the last row 999 then What will happen in
the following conditions?

Condition1: Delete all the rows and insert another row then.
What is the starting value for this auto incremented field user_pri_id ,
Condition2: Delete the last row(having the field value 999) and
insert another row then. What is the value for this auto incremented
field user_pri_id
A:73 In both cases let the value for auto increment field be n then next
row will have value n+1 i.e. 1000

Q:74 What are the advantages/disadvantages of MySQL and PHP?
A:74 Both of them are open source software (so free of cost), support
cross platform. php is faster then ASP and JSP.

Q:75 What is the difference between GROUP BY and ORDER BY in Sql?
A:75 ORDER BY [col1],[col2],…,[coln]; Tels DBMS according to what columns
it should sort the result. If two rows will hawe the same value in col1
it will try to sort them according to col2 and so on.GROUP BY
[col1],[col2],…,[coln]; Tels DBMS to group results with same value of
column col1. You can use COUNT(col1), SUM(col1), AVG(col1) with it, if
you want to count all items in group, sum all values or view average

Q:76 What is the difference between char and varchar data types?
A:76 Set char to occupy n bytes and it will take n bytes even if u r
storing a value of n-m bytes
Set varchar to occupy n bytes and it will take only the required space
and will not use the n bytes
eg. name char(15) will waste 10 bytes if we store ‘mizan’, if each char
takes a byte
eg. name varchar(15) will just use 5 bytes if we store ‘mizan’, if each
char takes a byte. rest 10 bytes will be free.

Q:77 What is the functionality of md5 function in PHP?
A:77 Calculate the md5 hash of a string. The hash is a 32-character
hexadecimal number. I use it to generate keys which I use to identify
users etc. If I add random no techniques to it the md5 generated now
will be totally different for the same string I am using.

Q:78 How can I load data from a text file into a table?
A:78 you can use LOAD DATA INFILE file_name; syntax to load data
from a text file. but you have to make sure thata) data is delimited
b) columns and data matched correctly

Q:79 How can we know the number of days between two given dates using
MySQL?

A:79 SELECT DATEDIFF(’2007-03-07′,’2005-01-01′);

Q:80 How can we know the number of days between two given dates using
PHP?

A:80 $date1 = date(’Y-m-d’);
$date2 = ‘2006-08-15′;
$days = (strtotime($date1) – strtotime($date2)) / (60 * 60 * 24);

 

Q:81 What is ‘float’ property in CSS?

A:81 The float property sets where an image or a text will appear in another element.

    

Q:82 What is descendant structure in CSS?

A:82 Descendant selectors are used to select elements that are descendants of another element in the document tree.For example, you may wish to target a specific <em> element on the page, but not all <em> elements. A sample document could contain the following code: <body>

<h1>Heading <em>here</em> </h1>

<p>Lorem ipsum dolor <em>sit</em> amet.</p>

</body> The document tree diagram (with the <em> element to be targeted) would be:Document tree showing descendant selectorsIf you use a type selector like the example below, you will select all <em> elements on the page:

 

em {color: blue; } However, if you use a descendant selector, you can refine the <em> elements that you select. The rule below will only select <em> elements that are descendants of <p> elements. If this rule is applied, the <em> element within the <h1> will not be colored blue.

 

p em {color: blue; } You can also jump levels in the document tree structure to select descendants. For example, the following code:

 

<body>

<p>Lorem ipsum dolor <em>sit</em> amet.</p>

<ul>

<li>item 1</li>

<li>item 2</li>

<li><em>item 3</em></li>

</ul>

</body> The document tree (with a third-level <em> element highlighted) would be:

 

Document tree showing descendant selectors

 

Using the following rule you can isolate any <em> element inside a <ul> element, without having to describe the <li> element. If this rule is applied, any <em> element within a <ul> element will be colored blue. However, the <em> element within the <p> will not be colored blue:

 

ul em {color: blue; } Descendant selectors are well supported across standards-compliant browsers.

    

Q:83 What is Child Descendant structure in CSS?

A:83

Child selectors

 

A child selector is used to select an element that is a direct child of another element (parent). Child selectors will not select all descendants, only direct children.

 

For example, you may wish to target an <em> that is a direct child of a <div>, but not other <em> elements that are descendants of the <div>. A sample document could contain the following code:

 

<body>

<h1>Heading <em>text</em></h1>

<div>

This is some <em>text</em>

<p>This is a paragraph of <em>text</em></p>

</div>

</body>

The document tree (highlighting the <em> that is a child of the <div>) would be:

 

Document tree showing child selector

 

Using the following rule you can target any <em> element that is a child of the <div>. Other <em> elements that are descendants but not direct children of the <div> will not be targeted.

 

div > em { color: blue; }

 

OR

 

div>em { color: blue; }

Child selectors are not supported by Windows Internet Explorer 5, 5.5 and 6, but are supported by most other standards-compliant browsers.

    

Q:84 How to create a class in JavaScript?

A:84 Classes can seem off-putting at first, but once you see the point of them, their use can be invaluable.We have already met objects. A computer object is a representation of a real object. For an estate agent the object may be a house, including information about the number of rooms and the price.An estate agent may have a lot of houses available. These houses all have different characteristics, and as objects they all go through the same processes. They are viewed, surveyed and bought, and so on.A full estate agent program would be difficult to demonstrate here, but we can introduce the use of classes.In this example, we have the house class. The house class produces house objects, all with object properties, such as number of rooms and price, and all having access to the same methods, such as sold and bought.

 

So a class can create objects with a group of properties and methods.

 

JavaScript doesn’t have a keyword specific to class, so we must go back to basics and develop classes in a different way. This isn’t very difficult.

Class Properties

 

Let us examine a very small estate agent program.

 

<HTML>

<HEAD>

<TITLE>Estate Agent</TITLE>

<SCRIPT>

function House(rooms,price,garage) {

this.rooms=rooms;

this.price=price;

this.garage=garage;

}

house1=new House(4,100000,false);

house2=new House(5,200000,true);

with (house1) document.write(’House 1 has ‘+rooms+’ rooms, ‘+(garage?’a’:’no’)+’ garage, and costs £’+price+’<BR>’);

with (house2) document.write(’House 2 has ‘+rooms+’ rooms, ‘+(garage?’a’:’no’)+’ garage, and costs £’+price+’<BR>’);

</SCRIPT>

</HEAD>

</HTML>

 

We define a House function that takes three parameters, rooms, price and garage. The function uses the this keyword to create an object.

 

When we call the House function, we assign the result to our variable, which becomes an object.

 

So, identical code would be:

 

house1=new Object();

house1.rooms=4;

house1.price=100000;

house1.garage=false;

 

We would have to type this in for all houses, which would be very tedious and is why we use the class structure instead.

 

When we display the details for a house, I have introduced the ternary operator, ‘?:’. The ternary operator is a compacted version of:

 

if (garage) str=’a’; else str=’no’;

 

(garage?’a’:’no’) means if garage is true, return ‘a’ else return ‘no’. Using the ternary operator removes a line of code, and avoids having to create a new variable.

Class Methods

 

The House class we have so far defined only contains object properties. We could add a method to replace the document.write() action we used before. (See example)

 

<HTML>

<HEAD>

<TITLE>Estate Agent 2</TITLE>

<SCRIPT>

function House(name,rooms,price,garage) {

this.name=name;

this.rooms=rooms;

this.price=price;

this.garage=garage;

this.view=view;

}

function view() {

with (this) document.write(name+’ has ‘+rooms+’ rooms, ‘+(garage?’a’:’no’)+’ garage, and costs £’+price+’<BR>’);

}

house1=new House(’House 1′,4,100000,false);

house2=new House(’Big House’,5,200000,true);

house1.view();

house2.view();

</SCRIPT>

</HEAD>

</HTML>

 

Much better!

 

Note how we must add another property, name, so that we can identify the house in question. This offers more flexibility than re-using the variable name, and the variable name is inaccessible anyway, i.e. it is very difficult, if not impossible, to get the view() function to use the string ‘house1′.

    

Q:85 Are namespaces are there in JavaScript?

A:81 A namespace is a container and allows you to bundle up all your functionality using a unique name. In JavaScript, a namespace is really just an object that you’ve attached all further methods, properties and objects. But it is not always necessary to use namespace.

    

Q:86 What is JSON? What are the notations used in JSON?

A:86 JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. It is based on a subset of the JavaScript Programming Language, Standard ECMA-262 3rd Edition – December 1999. JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.

    

Q:87 How to get Query String in PHP for http request?

A:87 $_GET[] and $_REQUEST[]

    

Q:88 How to get the http Request in PHP?

A:88 When PHP is used on a Web server to handle a HTTP request, it converts information submitted in the HTTP request as predefined variables:

 

    * $_GET – Associate array of variables submitted with GET method.

    * $_POST – Associate array of variables submitted with POST method.

    * $_COOKIE – Associate array of variables submitted as cookies.

    * $_REQUEST – Associate array of variables from $_GET, $_POST, and $_COOKIE.

    * $_SERVER – Associate array of all information from the server and the HTTP request.

 

    

Q:89 How you provide security for PHP application?

A:89 There are many ways to accomplish the security tasks but the most common 7 ways are1. Validate Input. Never trust your user and always filter input before taking it to any operation.2. Provide access control.3. Session ID protection4. preventing Cross Site Scripting (XSS) flaws

 

5. SQL injection vulnerabilities.

 

6. Turning off error reporting and exposing to the site for hackers. Instead use log file to catch exceptions

 

7. Effective Data handling

    

Q:90 What is SQL Injection in PHP security?

A:90 SQL injection attacks are extremely simple to defend against, but many applications are still vulnerable. Consider the following SQL statement:

 

<?php

$sql = “INSERT

        INTO   users (reg_username,

                      reg_password,

                      reg_email)

        VALUES (‘{$_POST[‘reg_username’]}’,

                ‘$reg_password’,

                ‘{$_POST[‘reg_email’]}’)”;

?>

 

This query is constructed with $_POST, which should immediately look suspicious.

 

Assume that this query is creating a new account. The user provides a desired username and an email address. The registration application generates a temporary password and emails it to the user to verify the email address. Imagine that the user enters the following as a username:

 

bad_guy’, ‘mypass’, ”), (‘good_guy

 

This certainly doesn’t look like a valid username, but with no data filtering in place, the application can’t tell. If a valid email address is given (shiflett@php.net, for example), and 1234 is what the application generates for the password, the SQL statement becomes the following:

 

<?php

 

$sql = “INSERT

        INTO   users (reg_username,

                      reg_password,

                      reg_email)

        VALUES (‘bad_guy’, ‘mypass’, ”),

          (‘good_guy’,

                ‘1234’,

                ‘shiflett@php.net’)”; ?>

 

Rather than the intended action of creating a single account (good_guy) with a valid email address, the application has been tricked into creating two accounts, and the user supplied every detail of the bad_guy account.

 

While this particular example might not seem so harmful, it should be clear that worse things could happen once an attacker can make modifications to your SQL statements.

 

For example, depending on the database you are using, it might be possible to send multiple queries to the database server in a single call. Thus, a user can potentially terminate the existing query with a semicolon and follow this with a query of the user’s choosing.

 

MySQL, until recently, does not allow multiple queries, so this particular risk is mitigated. Newer versions of MySQL allow multiple queries, but the corresponding PHP extension (ext/mysqli) requires that you use a separate function if you want to send multiple queries (mysqli_multi_query() instead of mysqli_query()). Only allowing a single query is safer, because it limits what an attacker can potentially do.

 

Protecting against SQL injection is easy:

 

    * Filter your data.This cannot be overstressed. With good data filtering in place, most security concerns are mitigated, and some are practically eliminated.

    * Quote your data.If your database allows it (MySQL does), put single quotes around all values in your SQL statements, regardless of the data type.

    * Escape your data.Sometimes valid data can unintentionally interfere with the format of the SQL statement itself. Use mysql_escape_string() or an escaping function native to your particular database. If there isn’t a specific one, addslashes() is a good last resort.

 

    

Q:91 What is cross site Scripting?

A:91 To understand what Cross Site Scripting is, let’s see a usual situation, common to many sites. Let’s say we are taking some information passed in on a querystring (the string after the (?) character within a URL), with the purpose of displaying the content of a variable, for example, the visitor’s name:

 

http://www.yourdomain.com/welcomedir/welcomepage.php?name=John

As we can see in this simple querystring, we are passing the visitor’s name as a parameter in the URL, and then displaying it on our “welcomepage.php” page with the following PHP code:

 

<?php

 

echo ‘Welcome to our site ’ . stripslashes($_GET[‘name’]);

 

?>

The result of this snippet is shown below:

 

Welcome to our site John

This is pretty simple and straightforward. We’re displaying the content of the “name” variable, by using the $_GET superglobal PHP array, as we have done probably hundreds of times. Everything seems to be fine. Now, what’s wrong with this code? Nothing really. But let’s modify the querystring by replacing our visitor’s name passed in the URL:

 

http://www.yourdomain.com/welcomedir/

welcomepage.php?name=John

with something like this:

 

http://www.yourdomain.com/welcomedir/

welcomepage.php?name=

<script language=javascript>alert

(‘Hey, you are going to be hijacked!’);</script>

Do you remember the PHP code included in our “welcome.php” page? Yes, you’re correct. When we modify the querystring, the following code is executed:

 

<?php

 

echo ‘Welcome to our site ‘ .

<script language=javascript> alert(‘Hey, you are going

to be hijacked!’);</script>

 

?>

The output of this code is an alert JavaScript box telling you “Hey, you are going be hijacked!” after the “Welcome to our site” phrase.

 

Very ugly stuff, right? That’s a simple example of the Cross Site Scripting vulnerability. This means that any pasted JavaScript code into the URL will be executed happily with no complaints at all.

 

    

Q:92 Which method do you follow to get a record from a million records? (Searching, …. not from database, from an array in php)

A:92 use array_search(), array_keys(), array_values(), array_key_exists(), and in_array().

    

Q:93 Which sorting method is lowest time consumable?

A:93 HeapSort, Merge sort are the lowest time consumable sorting algorithm.

    

Q:94 Which sorting method is lowest memory consumable?

A:9412341

Categories
MySQL PHP

PHP MySQL Interview Questions and Answers


PHP MySQL Interview Questions and Answers
What’s PHP
The PHP Hypertext Preprocessor is a programming language that allows web developers to create dynamic content that interacts with databases. PHP is basically used for developing web based software applications.
What Is a Session?
A session is a logical object created by the PHP engine to allow you to preserve data across subsequent HTTP requests.
There is only one session object available to your PHP scripts at any time. Data saved to the session by a script can be retrieved by the same script or another script when requested from the same visitor.
Sessions are commonly used to store temporary data to allow multiple PHP pages to offer a complete functional transaction for the same visitor.
What is meant by PEAR in php?
Answer1:
PEAR is the next revolution in PHP. This repository is bringing higher level programming to PHP. PEAR is a framework and distribution system for reusable PHP components. It eases installation by bringing an automated wizard, and packing the strength and experience of PHP users into a nicely organised OOP library. PEAR also provides a command-line interface that can be used to automatically install “packages”
Answer2:
PEAR is short for “PHP Extension and Application Repository” and is pronounced just like the fruit. The purpose of PEAR is to provide:
A structured library of open-sourced code for PHP users
A system for code distribution and package maintenance
A standard style for code written in PHP
The PHP Foundation Classes (PFC),
The PHP Extension Community Library (PECL),
A web site, mailing lists and download mirrors to support the PHP/PEAR community
PEAR is a community-driven project with the PEAR Group as the governing body. The project has been founded by Stig S. Bakken in 1999 and quite a lot of people have joined the project since then.
How can we know the number of days between two given dates using PHP?
Simple arithmetic:
$date1 = date(‘Y-m-d’);
$date2 = ‘2006-07-01’;
$days = (strtotime() – strtotime()) / (60 * 60 * 24);
echo “Number of days since ‘2006-07-01’: $days”;
How can we repair a MySQL table?
The syntex for repairing a mysql table is:
REPAIR TABLE tablename
REPAIR TABLE tablename QUICK
REPAIR TABLE tablename EXTENDED
This command will repair the table specified.
If QUICK is given, MySQL will do a repair of only the index tree.
If EXTENDED is given, it will create index row by row.
What is the difference between $message and $$message?
Anwser 1:
$message is a simple variable whereas $$message is a reference variable. Example:
$user = ‘bob’
is equivalent to
$holder = ‘user’;
$$holder = ‘bob’;
Anwser 2:
They are both variables. But $message is a variable with a fixed name. $$message is a variable who’s name is stored in $message. For example, if $message contains “var”, $$message is the same as $var.
What Is a Persistent Cookie?
A persistent cookie is a cookie which is stored in a cookie file permanently on the browser’s computer. By default, cookies are created as temporary cookies which stored only in the browser’s memory. When the browser is closed, temporary cookies will be erased. You should decide when to use temporary cookies and when to use persistent cookies based on their differences:

  • Temporary cookies can not be used for tracking long-term information.
  • Persistent cookies can be used for tracking long-term information.
  • Temporary cookies are safer because no programs other than the browser can access them.
  • Persistent cookies are less secure because users can open cookie files see the cookie values.

What does a special set of tags do in PHP?
What does a special set of tags <?= and ?> do in PHP?
The output is displayed directly to the browser.
How do you define a constant?
Via define() directive, like define (“MYCONSTANT”, 100);
What are the differences between require and include, include_once?
Anwser 1:
require_once() and include_once() are both the functions to include and evaluate the specified file only once. If the specified file is included previous to the present call occurrence, it will not be done again.
But require() and include() will do it as many times they are asked to do.
Anwser 2:
The include_once() statement includes and evaluates the specified file during the execution of the script. This is a behavior similar to the include() statement, with the only difference being that if the code from a file has already been included, it will not be included again. The major difference between include() and require() is that in failure include() produces a warning message whereas require() produces a fatal errors.
Anwser 3:
All three are used to an include file into the current page.
If the file is not present, require(), calls a fatal error, while in include() does not.
The include_once() statement includes and evaluates the specified file during the execution of the script. This is a behavior similar to the include() statement, with the only difference being that if the code from a file has already been included, it will not be included again. It des not call a fatal error if file not exists. require_once() does the same as include_once(), but it calls a fatal error if file not exists.
Anwser 4:
File will not be included more than once. If we want to include a file once only and further calling of the file will be ignored then we have to use the PHP function include_once(). This will prevent problems with function redefinitions, variable value reassignments, etc.
What is meant by urlencode and urldecode?
Anwser 1:
urlencode() returns the URL encoded version of the given string. URL coding converts special characters into % signs followed by two hex digits. For example: urlencode(“10.00%”) will return “10%2E00%25”. URL encoded strings are safe to be used as part of URLs.
urldecode() returns the URL decoded version of the given string.
Anwser 2:
string urlencode(str) – Returns the URL encoded version of the input string. String values to be used in URL query string need to be URL encoded. In the URL encoded version:
Alphanumeric characters are maintained as is.
Space characters are converted to “+” characters.
Other non-alphanumeric characters are converted “%” followed by two hex digits representing the converted character.
string urldecode(str) – Returns the original string of the input URL encoded string.
For example:
$discount =”10.00%”;
$url = “http://domain.com/submit.php?disc=”.urlencode($discount);
echo $url;
You will get “http://domain.com/submit.php?disc=10%2E00%25”.
How To Get the Uploaded File Information in the Receiving Script?
Once the Web server received the uploaded file, it will call the PHP script specified in the form action attribute to process them. This receiving PHP script can get the uploaded file information through the predefined array called $_FILES. Uploaded file information is organized in $_FILES as a two-dimensional array as:

  • $_FILES[$fieldName][‘name’] – The Original file name on the browser system.
  • $_FILES[$fieldName][‘type’] – The file type determined by the browser.
  • $_FILES[$fieldName][‘size’] – The Number of bytes of the file content.
  • $_FILES[$fieldName][‘tmp_name’] – The temporary filename of the file in which the uploaded file was stored on the server.
  • $_FILES[$fieldName][‘error’] – The error code associated with this file upload.

The $fieldName is the name used in the <INPUT TYPE=FILE, NAME=fieldName>.
What is the difference between mysql_fetch_object and mysql_fetch_array?
MySQL fetch object will collect first single matching record where mysql_fetch_array will collect all matching records from the table in an array
How can I execute a PHP script using command line?
Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument. For example, “php myScript.php”, assuming “php” is the command to invoke the CLI program.
Be aware that if your PHP script was written for the Web CGI interface, it may not execute properly in command line environment.
I am trying to assign a variable the value of 0123, but it keeps coming up with a different number, what’s the problem?
PHP Interpreter treats numbers beginning with 0 as octal. Look at the similar PHP interview questions for more numeric problems.
Would I use print “$a dollars” or “{$a} dollars” to print out the amount of dollars in this example?
In this example it wouldn’t matter, since the variable is all by itself, but if you were to print something like “{$a},000,000 mln dollars”, then you definitely need to use the braces.
What are the different tables present in MySQL? Which type of table is generated when we are creating a table in the following syntax: create table employee(eno int(2),ename varchar(10))?
Total 5 types of tables we can create
1. MyISAM
2. Heap
3. Merge
4. INNO DB
5. ISAM
MyISAM is the default storage engine as of MySQL 3.23. When you fire the above create query MySQL will create a MyISAM table.
How To Create a Table?
If you want to create a table, you can run the CREATE TABLE statement as shown in the following sample script:
<?php
include “mysql_connection.php”;
$sql = “CREATE TABLE fyi_links (”
. ” id INTEGER NOT NULL”
. “, url VARCHAR(80) NOT NULL”
. “, notes VARCHAR(1024)”
. “, counts INTEGER”
. “, time TIMESTAMP DEFAULT sysdate()”
. “)”;
if (mysql_query($sql, $con)) {
print(“Table fyi_links created.\n”);
} else {
print(“Table creation failed.\n”);
}
mysql_close($con);
?>
Remember that mysql_query() returns TRUE/FALSE on CREATE statements. If you run this script, you will get something like this:
Table fyi_links created.
How can we encrypt the username and password using PHP?
Answer1
You can encrypt a password with the following Mysql>SET PASSWORD=PASSWORD(“Password”);
Answer2
You can use the MySQL PASSWORD() function to encrypt username and password. For example,
INSERT into user (password, …) VALUES (PASSWORD($password”)), …);
How do you pass a variable by value?
Just like in C++, put an ampersand in front of it, like $a = &$b
WHAT IS THE FUNCTIONALITY OF THE FUNCTIONS STRSTR() AND STRISTR()?
string strstr ( string haystack, string needle ) returns part of haystack string from the first occurrence of needle to the end of haystack. This function is case-sensitive.
stristr() is idential to strstr() except that it is case insensitive.
When are you supposed to use endif to end the conditional statement?
When the original if was followed by : and then the code block without braces.
How can we send mail using JavaScript?
No. There is no way to send emails directly using JavaScript.
But you can use JavaScript to execute a client side email program send the email using the “mailto” code. Here is an example:
function myfunction(form)
{
tdata=document.myform.tbox1.value;
location=”mailto:mailid@domain.com?subject=…”;
return true;
}
What is the functionality of the function strstr and stristr?
strstr() returns part of a given string from the first occurrence of a given substring to the end of the string. For example: strstr(“user@example.com”,”@”) will return “@example.com”.
stristr() is idential to strstr() except that it is case insensitive.
What is the difference between ereg_replace() and eregi_replace()?
eregi_replace() function is identical to ereg_replace() except that it ignores case distinction when matching alphabetic characters.
How do I find out the number of parameters passed into function9. ?
func_num_args() function returns the number of parameters passed in.
What is the purpose of the following files having extensions: frm, myd, and myi? What these files contain?
In MySQL, the default table type is MyISAM.
Each MyISAM table is stored on disk in three files. The files have names that begin with the table name and have an extension to indicate the file type.
The ‘.frm’ file stores the table definition.
The data file has a ‘.MYD’ (MYData) extension.
The index file has a ‘.MYI’ (MYIndex) extension,
If the variable $a is equal to 5 and variable $b is equal to character a, what’s the value of $$b?
5, it’s a reference to existing variable.

Write a query for the following question
The table tbl_sites contains the following data:
—————————————
Userid sitename country
—————————————
1 sureshbabu indian
2 PHPprogrammer andhra
3 PHP.net usa
4 PHPtalk.com germany
5 MySQL.com usa
6 sureshbabu canada
7 PHPbuddy.com pakistan
8. PHPtalk.com austria
9. PHPfreaks.com sourthafrica
10. PHPsupport.net russia
11. sureshbabu australia
12. sureshbabu nepal
13. PHPtalk.com italy
Write a select query that will be displayed the duplicated site name and how many times it is duplicated? …
SELECT sitename, COUNT(*) AS NumOccurrences
FROM tbl_sites
GROUP BY sitename HAVING COUNT(*) > 1
How To Protect Special Characters in Query String?
If you want to include special characters like spaces in the query string, you need to protect them by applying the urlencode() translation function. The script below shows how to use urlencode():
<?php
print(“<html>”);
print(“<p>Please click the links below”
.” to submit comments about FYICenter.com:</p>”);
$comment = ‘I want to say: “It\’s a good site! :->”‘;
$comment = urlencode($comment);
print(“<p>”
.”<a href=\”processing_forms.php?name=Guest&comment=$comment\”>”
.”It’s an excellent site!</a></p>”);
$comment = ‘This visitor said: “It\’s an average site! :-(“‘;
$comment = urlencode($comment);
print(“<p>”
.'<a href=”processing_forms.php?’.$comment.'”>’
.”It’s an average site.</a></p>”);
print(“</html>”);
?>
Are objects passed by value or by reference?
Everything is passed by value.
What are the differences between DROP a table and TRUNCATE a table?
DROP TABLE table_name – This will delete the table and its data.
TRUNCATE TABLE table_name – This will delete the data of the table, but not the table definition.
What are the differences between GET and POST methods in form submitting, give the case where we can use GET and we can use POST methods?
Anwser 1:
When we submit a form, which has the GET method it displays pair of name/value used in the form at the address bar of the browser preceded by url. Post method doesn’t display these values.
Anwser 2:
When you want to send short or small data, not containing ASCII characters, then you can use GET” Method. But for long data sending, say more then 100 character you can use POST method.
Once most important difference is when you are sending the form with GET method. You can see the output which you are sending in the address bar. Whereas if you send the form with POST” method then user can not see that information.
Anwser 3:
What are “GET” and “POST”?
GET and POST are methods used to send data to the server: With the GET method, the browser appends the data onto the URL. With the Post method, the data is sent as “standard input.”
Major Difference
In simple words, in POST method data is sent by standard input (nothing shown in URL when posting while in GET method data is sent through query string.
Ex: Assume we are logging in with username and password.
GET: we are submitting a form to login.php, when we do submit or similar action, values are sent through visible query string (notice ./login.php?username=…&password=… as URL when executing the script login.php) and is retrieved by login.php by $_GET[‘username’] and $_GET[‘password’].
POST: we are submitting a form to login.php, when we do submit or similar action, values are sent through invisible standard input (notice ./login.php) and is retrieved by login.php by $_POST[‘username’] and $_POST[‘password’].
POST is assumed more secure and we can send lot more data than that of GET method is limited (they say Internet Explorer can take care of maximum 2083 character as a query string).
Anwser 4:
In the get method the data made available to the action page ( where data is received ) by the URL so data can be seen in the address bar. Not advisable if you are sending login info like password etc. In the post method the data will be available as data blocks and not as query string in case of get method.
Anwser 5:
When we submit a form, which has the GET method it pass value in the form of query string (set of name/value pair) and display along with URL. With GET we can a small data submit from the form (a set of 255 character) whereas Post method doesn’t display value with URL. It passes value in the form of Object and we can submit large data from the form.
Anwser 6:
On the server side, the main difference between GET and POST is where the submitted is stored. The $_GET array stores data submitted by the GET method. The $_POST array stores data submitted by the POST method.
On the browser side, the difference is that data submitted by the GET method will be displayed in the browser’s address field. Data submitted by the POST method will not be displayed anywhere on the browser.
GET method is mostly used for submitting a small amount and less sensitive data. POST method is mostly used for submitting a large amount or sensitive data.
How do you call a constructor for a parent class?
parent::constructor($value)
WHAT ARE THE DIFFERENT TYPES OF ERRORS IN PHP?
Here are three basic types of runtime errors in PHP:
1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script – for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all – although you can change this default behavior.
2. Warnings: These are more serious errors – for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.
3. Fatal errors: These are critical errors – for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP’s default behavior is to display them to the user when they take place.
Internally, these variations are represented by twelve different error types
What’s the special meaning of __sleep and __wakeup?
__sleep returns the array of all the variables than need to be saved, while __wakeup retrieves them.
How can we submit a form without a submit button?
If you don’t want to use the Submit button to submit a form, you can use normal hyper links to submit a form. But you need to use some JavaScript code in the URL of the link. For example:
<a href=”javascript: document.myform.submit();”>Submit Me</a>
Why doesn’t the following code print the newline properly? <?php $str = ‘Hello, there.\nHow are you?\nThanks for visiting fyicenter’; print $str; ?>
Because inside the single quotes the \n character is not interpreted as newline, just as a sequence of two characters – \ and n.
Would you initialize your strings with single quotes or double quotes?
Since the data inside the single-quoted string is not parsed for variable substitution, it’s always a better idea speed-wise to initialize a string with single quotes, unless you specifically need variable substitution.
How can we extract string ‘abc.com ‘ from a string http://info@abc.com using regular expression of php?

We can use the preg_match() function with "/.*@(.*)$/" as
the regular expression pattern. For example:
preg_match("/.*@(.*)$/","http://info@abc.com",$data);
echo $data[1];

What is the difference between the functions unlink and unset?
unlink() is a function for file system handling. It will simply delete the file in context.
unset() is a function for variable management. It will make a variable undefined.
How come the code works, but doesn’t for two-dimensional array of mine?
Any time you have an array with more than one dimension, complex parsing syntax is required. print “Contents: {$arr[1][2]}” would’ve worked.
How can we register the variables into a session?
session_register($session_var);
$_SESSION[‘var’] = ‘value’;
What is the difference between characters 23 and \x23?
The first one is octal 23, the second is hex 23.
How can we submit form without a submit button?
We can use a simple JavaScript code linked to an event trigger of any form field. In the JavaScript code, we can call the document.form.submit() function to submit the form. For example: <input type=button value=”Save” onClick=”document.form.submit()”>
How can we create a database using PHP and mysql?
We can create MySQL database with the use of mysql_create_db($databaseName) to create a database.
How many ways we can retrieve the date in result set of mysql using php?
As individual objects so single record or as a set or arrays.
Can we use include (“abc.php”) two times in a php page “makeit.php”?
Yes.
For printing out strings, there are echo, print and printf. Explain the differences.
echo is the most primitive of them, and just outputs the contents following the construct to the screen. print is also a construct (so parentheses are optional when calling it), but it returns TRUE on successful output and FALSE if it was unable to print out the string. However, you can pass multiple parameters to echo, like:
<?php echo ‘Welcome ‘, ‘to’, ‘ ‘, ‘fyicenter!’; ?>
and it will output the string “Welcome to fyicenter!” print does not take multiple parameters. It is also generally argued that echo is faster, but usually the speed advantage is negligible, and might not be there for future versions of PHP. printf is a function, not a construct, and allows such advantages as formatted output, but it’s the slowest way to print out data out of echo, print and printf.
I am writing an application in PHP that outputs a printable version of driving directions. It contains some long sentences, and I am a neat freak, and would like to make sure that no line exceeds 50 characters. How do I accomplish that with PHP?
On large strings that need to be formatted according to some length specifications, use wordwrap() or chunk_split().
What’s the output of the ucwords function in this example?
$formatted = ucwords(“FYICENTER IS COLLECTION OF INTERVIEW QUESTIONS”);
print $formatted;
What will be printed is FYICENTER IS COLLECTION OF INTERVIEW QUESTIONS.
ucwords() makes every first letter of every word capital, but it does not lower-case anything else. To avoid this, and get a properly formatted string, it’s worth using strtolower() first.

What’s the difference between htmlentities() and htmlspecialchars()?
htmlspecialchars only takes care of <, >, single quote ‘, double quote ” and ampersand. htmlentities translates all occurrences of character sequences that have different meaning in HTML.
How can we extract string “abc.com” from a string “mailto:info@abc.com?subject=Feedback” using regular expression of PHP?
$text = “mailto:info@abc.com?subject=Feedback”;
preg_match(‘|.*@([^?]*)|’, $text, $output);
echo $output[1];
Note that the second index of $output, $output[1], gives the match, not the first one, $output[0].
So if md5() generates the most secure hash, why would you ever use the less secure crc32() and sha1()?
Crypto usage in PHP is simple, but that doesn’t mean it’s free. First off, depending on the data that you’re encrypting, you might have reasons to store a 32-bit value in the database instead of the 160-bit value to save on space. Second, the more secure the crypto is, the longer is the computation time to deliver the hash value. A high volume site might be significantly slowed down, if frequent md5() generation is required.
How can we destroy the session, how can we unset the variable of a session?
session_unregister() – Unregister a global variable from the current session
session_unset() – Free all session variables
What are the different functions in sorting an array?
Sorting functions in PHP:
asort()
arsort()
ksort()
krsort()
uksort()
sort()
natsort()
rsort()
How can we know the count/number of elements of an array?
2 ways:
a) sizeof($array) – This function is an alias of count()
b) count($urarray) – This function returns the number of elements in an array.
Interestingly if you just pass a simple var instead of an array, count() will return 1.
How many ways we can pass the variable through the navigation between the pages?
At least 3 ways:
1. Put the variable into session in the first page, and get it back from session in the next page.
2. Put the variable into cookie in the first page, and get it back from the cookie in the next page.
3. Put the variable into a hidden form field, and get it back from the form in the next page.
What is the maximum length of a table name, a database name, or a field name in MySQL?
Database name: 64 characters
Table name: 64 characters
Column name: 64 characters
How many values can the SET function of MySQL take?
MySQL SET function can take zero or more values, but at the maximum it can take 64 values.
What are the other commands to know the structure of a table using MySQL commands except EXPLAIN command?
DESCRIBE table_name;
How can we find the number of rows in a table using MySQL?
Use this for MySQL
SELECT COUNT(*) FROM table_name;
What’s the difference between md5(), crc32() and sha1() crypto on PHP?
The major difference is the length of the hash generated. CRC32 is, evidently, 32 bits, while sha1() returns a 128 bit value, and md5() returns a 160 bit value. This is important when avoiding collisions.
How can we find the number of rows in a result set using PHP?
Here is how can you find the number of rows in a result set in PHP:
$result = mysql_query($any_valid_sql, $database_link);
$num_rows = mysql_num_rows($result);
echo “$num_rows rows found”;
How many ways we can we find the current date using MySQL?
SELECT CURDATE();
SELECT CURRENT_DATE();
SELECT CURTIME();
SELECT CURRENT_TIME();
Give the syntax of GRANT commands?
The generic syntax for GRANT is as following
GRANT [rights] on [database] TO [username@hostname] IDENTIFIED BY [password]
Now rights can be:
a) ALL privilages
b) Combination of CREATE, DROP, SELECT, INSERT, UPDATE and DELETE etc.
We can grant rights on all databse by usingh *.* or some specific database by database.* or a specific table by database.table_name.
Give the syntax of REVOKE commands?
The generic syntax for revoke is as following
REVOKE [rights] on [database] FROM [username@hostname]
Now rights can be:
a) ALL privilages
b) Combination of CREATE, DROP, SELECT, INSERT, UPDATE and DELETE etc.
We can grant rights on all databse by usingh *.* or some specific database by database.* or a specific table by database.table_name.
Answer the questions with the following assumption
The structure of table view buyers is as follows:

+-------------+-------------+------+-----+---------+----------------+
| Field       | Type        | Null | Key | Default | Extra          |
+-------------+-------------+------+-----+---------+----------------+
| user_pri_id | int(15)     |      | PRI | NULL    | auto_increment |
| userid      | varchar(10) | YES  |     | NULL    |                |
+-------------+-------------+------+-----+---------+----------------+

The value of user_pri_id of the last row is 2345. What will happen in the following conditions?
Condition 1: Delete all the rows and insert another row. What is the starting value for this auto incremented field user_pri_id?
Condition 2: Delete the last row (having the field value 2345) and insert another row. What is the value for this auto incremented field user_pri_id?
In both conditions, the value of this auto incremented field user_pri_id is 2346.
What is the difference between CHAR and VARCHAR data types?
CHAR is a fixed length data type. CHAR(n) will take n characters of storage even if you enter less than n characters to that column. For example, “Hello!” will be stored as “Hello! ” in CHAR(10) column.
VARCHAR is a variable length data type. VARCHAR(n) will take only the required storage for the actual number of characters entered to that column. For example, “Hello!” will be stored as “Hello!” in VARCHAR(10) column.
How can we encrypt and decrypt a data present in a mysql table using mysql?
AES_ENCRYPT() and AES_DECRYPT()
Will comparison of string “10” and integer 11 work in PHP?
Yes, internally PHP will cast everything to the integer type, so numbers 10 and 11 will be compared.
What is the functionality of MD5 function in PHP?
string md5(string)
It calculates the MD5 hash of a string. The hash is a 32-character hexadecimal number.
How can I load data from a text file into a table?
The MySQL provides a LOAD DATA INFILE command. You can load data from a file. Great tool but you need to make sure that:
a) Data must be delimited
b) Data fields must match table columns correctly
How can we know the number of days between two given dates using MySQL?
Use DATEDIFF()
SELECT DATEDIFF(NOW(),’2006-07-01′);
How can we change the name of a column of a table?
This will change the name of column:
ALTER TABLE table_name CHANGE old_colm_name new_colm_name
How can we change the data type of a column of a table?
This will change the data type of a column:
ALTER TABLE table_name CHANGE colm_name same_colm_name [new data type]
What is the difference between GROUP BY and ORDER BY in SQL?
To sort a result, use an ORDER BY clause.
The most general way to satisfy a GROUP BY clause is to scan the whole table and create a new temporary table where all rows from each group are consecutive, and then use this temporary table to discover groups and apply aggregate functions (if any).
ORDER BY [col1],[col2],…[coln]; Tells DBMS according to what columns it should sort the result. If two rows will hawe the same value in col1 it will try to sort them according to col2 and so on.
GROUP BY [col1],[col2],…[coln]; Tells DBMS to group (aggregate) results with same value of column col1. You can use COUNT(col1), SUM(col1), AVG(col1) with it, if you want to count all items in group, sum all values or view average.
What is meant by MIME?
Answer 1:
MIME is Multipurpose Internet Mail Extensions is an Internet standard for the format of e-mail. However browsers also uses MIME standard to transmit files. MIME has a header which is added to a beginning of the data. When browser sees such header it shows the data as it would be a file (for example image)
Some examples of MIME types:
audio/x-ms-wmp
image/png
aplication/x-shockwave-flash
Answer 2:
Multipurpose Internet Mail Extensions.
WWW’s ability to recognize and handle files of different types is largely dependent on the use of the MIME (Multipurpose Internet Mail Extensions) standard. The standard provides for a system of registration of file types with information about the applications needed to process them. This information is incorporated into Web server and browser software, and enables the automatic recognition and display of registered file types. …
How can we know that a session is started or not?
A session starts by session_start() function.
This session_start() is always declared in header portion. it always declares first. then we write session_register().
What are the differences between mysql_fetch_array(), mysql_fetch_object(), mysql_fetch_row()?
Answer 1:
mysql_fetch_array() -> Fetch a result row as a combination of associative array and regular array.
mysql_fetch_object() -> Fetch a result row as an object.
mysql_fetch_row() -> Fetch a result set as a regular array().
Answer 2:
The difference between mysql_fetch_row() and mysql_fetch_array() is that the first returns the results in a numeric array ($row[0], $row[1], etc.), while the latter returns a the results an array containing both numeric and associative keys ($row[‘name’], $row[’email’], etc.). mysql_fetch_object() returns an object ($row->name, $row->email, etc.).
If we login more than one browser windows at the same time with same user and after that we close one window, then is the session is exist to other windows or not? And if yes then why? If no then why?
Session depends on browser. If browser is closed then session is lost. The session data will be deleted after session time out. If connection is lost and you recreate connection, then session will continue in the browser.
What are the MySQL database files stored in system ?
Data is stored in name.myd
Table structure is stored in name.frm
Index is stored in name.myi
What is the difference between PHP4 and PHP5?
PHP4 cannot support oops concepts and Zend engine 1 is used.
PHP5 supports oops concepts and Zend engine 2 is used.
Error supporting is increased in PHP5.
XML and SQLLite will is increased in PHP5.
Can we use include(abc.PHP) two times in a PHP page makeit.PHP”?
Yes we can include that many times we want, but here are some things to make sure of:
(including abc.PHP, the file names are case-sensitive)
there shouldn’t be any duplicate function names, means there should not be functions or classes or variables with the same name in abc.PHP and makeit.php
What are the differences between mysql_fetch_array(), mysql_fetch_object(), mysql_fetch_row()?
mysql_fetch_array – Fetch a result row as an associative array and a numeric array.
mysql_fetch_object – Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows
mysql_fetch_row() – Fetches one row of data from the result associated with the specified result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0.
What is meant by nl2br()?
Anwser1:
nl2br() inserts a HTML tag <br> before all new line characters \n in a string.
echo nl2br(“god bless \n you”);
output:
god bless<br>
you
How can we encrypt and decrypt a data presented in a table using MySQL?
You can use functions: AES_ENCRYPT() and AES_DECRYPT() like:
AES_ENCRYPT(str, key_str)
AES_DECRYPT(crypt_str, key_str)
How can I retrieve values from one database server and store them in other database server using PHP?
For this purpose, you can first read the data from one server into session variables. Then connect to other server and simply insert the data into the database.
WHO IS THE FATHER OF PHP AND WHAT IS THE CURRENT VERSION OF PHP AND MYSQL?
Rasmus Lerdorf.
PHP 5.1. Beta
MySQL 5.0
IN HOW MANY WAYS WE CAN RETRIEVE DATA IN THE RESULT SET OF MYSQL USING PHP?
mysql_fetch_array – Fetch a result row as an associative array, a numeric array, or both
mysql_fetch_assoc – Fetch a result row as an associative array
mysql_fetch_object – Fetch a result row as an object
mysql_fetch_row —- Get a result row as an enumerated array
What are the functions for IMAP?
imap_body – Read the message body
imap_check – Check current mailbox
imap_delete – Mark a message for deletion from current mailbox
imap_mail – Send an email message
What are encryption functions in PHP?
CRYPT()
MD5()
What is the difference between htmlentities() and htmlspecialchars()?
htmlspecialchars() – Convert some special characters to HTML entities (Only the most widely used)
htmlentities() – Convert ALL special characters to HTML entities
What is the functionality of the function htmlentities?
htmlentities() – Convert all applicable characters to HTML entities
This function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities.
How can we get the properties (size, type, width, height) of an image using php image functions?
To know the image size use getimagesize() function
To know the image width use imagesx() function
To know the image height use imagesy() function
How can we increase the execution time of a php script?
By the use of void set_time_limit(int seconds)
Set the number of seconds a script is allowed to run. If this is reached, the script returns a fatal error. The default limit is 30 seconds or, if it exists, the max_execution_time value defined in the php.ini. If seconds is set to zero, no time limit is imposed.
When called, set_time_limit() restarts the timeout counter from zero. In other words, if the timeout is the default 30 seconds, and 25 seconds into script execution a call such as set_time_limit(20) is made, the script will run for a total of 45 seconds before timing out.
HOW CAN WE TAKE A BACKUP OF A MYSQL TABLE AND HOW CAN WE RESTORE IT?
Answer 1:
Create a full backup of your database: shell> mysqldump tab=/path/to/some/dir opt db_name
Or: shell> mysqlhotcopy db_name /path/to/some/dir
The full backup file is just a set of SQL statements, so restoring it is very easy:
shell> mysql “.”Executed”;
Answer 2:
To backup: BACKUP TABLE tbl_name TO /path/to/backup/directory
’ To restore: RESTORE TABLE tbl_name FROM /path/to/backup/directory
mysqldump: Dumping Table Structure and Data
Utility to dump a database or a collection of database for backup or for transferring the data to another SQL server (not necessarily a MySQL server). The dump will contain SQL statements to create the table and/or populate the table.
-t, no-create-info
Don’t write table creation information (the CREATE TABLE statement).
-d, no-data
Don’t write any row information for the table. This is very useful if you just want to get a dump of the structure for a table!
How to set cookies?
setcookie(‘variable’,’value’,’time’)
;
variable – name of the cookie variable
value – value of the cookie variable
time – expiry time
Example: setcookie(‘Test’,$i,time()+3600);
Test – cookie variable name
$i – value of the variable ‘Test’
time()+3600 – denotes that the cookie will expire after an one hour
How to reset/destroy a cookie
Reset a cookie by specifying expire time in the past:
Example: setcookie(‘Test’,$i,time()-3600); // already expired time
Reset a cookie by specifying its name only
Example: setcookie(‘Test’);
WHAT TYPES OF IMAGES THAT PHP SUPPORTS?
Using imagetypes() function to find out what types of images are supported in your PHP engine.
imagetypes() – Returns the image types supported.
This function returns a bit-field corresponding to the image formats supported by the version of GD linked into PHP. The following bits are returned, IMG_GIF | IMG_JPG | IMG_PNG | IMG_WBMP | IMG_XPM.
CHECK IF A VARIABLE IS AN INTEGER IN JAVASCRIPT
var myValue =9.8;
if(parseInt(myValue)== myValue)
alert(‘Integer’);
else
alert(‘Not an integer’);
Tools used for drawing ER diagrams.
Case Studio
Smart Draw
How can I know that a variable is a number or not using a JavaScript?
Answer 1:
bool is_numeric( mixed var)
Returns TRUE if var is a number or a numeric string, FALSE otherwise.
Answer 2:
Definition and Usage
The isNaN() function is used to check if a value is not a number.
Syntax
isNaN(number)
Parameter Description
number Required. The value to be tested
How can we submit from without a submit button?
Trigger the JavaScript code on any event ( like onSelect of drop down list box, onfocus, etc ) document.myform.submit(); This will submit the form.
How many ways can we get the value of current session id?
session_id() returns the session id for the current session.
How can we destroy the cookie?
Set the cookie with a past expiration time.
What are the current versions of Apache, PHP, and MySQL?
PHP: PHP 5.1.2
MySQL: MySQL 5.1
Apache: Apache 2.1
What are the reasons for selecting LAMP (Linux, Apache, MySQL, Php) instead of combination of other software programs, servers and operating systems?
All of those are open source resource. Security of linux is very very more than windows. Apache is a better server that IIS both in functionality and security. Mysql is world most popular open source database. Php is more faster that asp or any other scripting language.
What are the features and advantages of OBJECT ORIENTED PROGRAMMING?
One of the main advantages of OO programming is its ease of modification; objects can easily be modified and added to a system there by reducing maintenance costs. OO programming is also considered to be better at modeling the real world than is procedural programming. It allows for more complicated and flexible interactions. OO systems are also easier for non-technical personnel to understand and easier for them to participate in the maintenance and enhancement of a system because it appeals to natural human cognition patterns. For some systems, an OO approach can speed development time since many objects are standard across systems and can be reused. Components that manage dates, shipping, shopping carts, etc. can be purchased and easily modified for a specific system.
What is the use of friend function?
Friend functions
Sometimes a function is best shared among a number of different classes. Such functions can be declared either as member functions of one class or as global functions. In either case they can be set to be friends of other classes, by using a friend specifier in the class that is admitting them. Such functions can use all attributes of the class which names them as a friend, as if they were themselves members of that class.
A friend declaration is essentially a prototype for a member function, but instead of requiring an implementation with the name of that class attached by the double colon syntax, a global function or member function of another class provides the match.
class mylinkage
{
private:
mylinkage * prev;
mylinkage * next;
protected:
friend void set_prev(mylinkage* L, mylinkage* N);
void set_next(mylinkage* L);
public:
mylinkage * succ();
mylinkage * pred();
mylinkage();
};
void mylinkage::set_next(mylinkage* L) { next = L; }
void set_prev(mylinkage * L, mylinkage * N ) { N->prev = L; }
Friends in other classes
It is possible to specify a member function of another class as a friend as follows:
class C
{
friend int B::f1();
};
class B
{
int f1();
};
It is also possible to specify all the functions in another class as friends, by specifying the entire class as a friend.
class A
{
friend class B;
};
Friend functions allow binary operators to be defined which combine private data in a pair of objects. This is particularly powerful when using the operator overloading features of C++. We will return to it when we look at overloading.
How can we get second of the current time using date function?
$second = date(“s”);
What is the maximum size of a file that can be uploaded using PHP and how can we change this?
You can change maximum size of a file set upload_max_filesize variable in php.ini file
How can I make a script that can be bilingual (supports English, German)?
You can change charset variable in above line in the script to support bilanguage.
What are the difference between abstract class and interface?
Abstract class: abstract classes are the class where one or more methods are abstract but not necessarily all method has to be abstract. Abstract methods are the methods, which are declare in its class but not define. The definition of those methods must be in its extending class.
Interface: Interfaces are one type of class where all the methods are abstract. That means all the methods only declared but not defined. All the methods must be define by its implemented class.
What are the advantages of stored procedures, triggers, indexes?
A stored procedure is a set of SQL commands that can be compiled and stored in the server. Once this has been done, clients don’t need to keep re-issuing the entire query but can refer to the stored procedure. This provides better overall performance because the query has to be parsed only once, and less information needs to be sent between the server and the client. You can also raise the conceptual level by having libraries of functions in the server. However, stored procedures of course do increase the load on the database server system, as more of the work is done on the server side and less on the client (application) side. Triggers will also be implemented. A trigger is effectively a type of stored procedure, one that is invoked when a particular event occurs. For example, you can install a stored procedure that is triggered each time a record is deleted from a transaction table and that stored procedure automatically deletes the corresponding customer from a customer table when all his transactions are deleted. Indexes are used to find rows with specific column values quickly. Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. The larger the table, the more this costs. If the table has an index for the columns in question, MySQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data. If a table has 1,000 rows, this is at least 100 times faster than reading sequentially. If you need to access most of the rows, it is faster to read sequentially, because this minimizes disk seeks.
What is maximum size of a database in mysql?
If the operating system or filesystem places a limit on the number of files in a directory, MySQL is bound by that constraint. The efficiency of the operating system in handling large numbers of files in a directory can place a practical limit on the number of tables in a database. If the time required to open a file in the directory increases significantly as the number of files increases, database performance can be adversely affected.
The amount of available disk space limits the number of tables.
MySQL 3.22 had a 4GB (4 gigabyte) limit on table size. With the MyISAM storage engine in MySQL 3.23, the maximum table size was increased to 65536 terabytes (2567 – 1 bytes). With this larger allowed table size, the maximum effective table size for MySQL databases is usually determined by operating system constraints on file sizes, not by MySQL internal limits.
The InnoDB storage engine maintains InnoDB tables within a tablespace that can be created from several files. This allows a table to exceed the maximum individual file size. The tablespace can include raw disk partitions, which allows extremely large tables. The maximum tablespace size is 64TB.
The following table lists some examples of operating system file-size limits. This is only a rough guide and is not intended to be definitive. For the most up-to-date information, be sure to check the documentation specific to your operating system.
Operating System File-size Limit
Linux 2.2-Intel 32-bit 2GB (LFS: 4GB)
Linux 2.4+ (using ext3 filesystem) 4TB
Solaris 9/10 16TB
NetWare w/NSS filesystem 8TB
Win32 w/ FAT/FAT32 2GB/4GB
Win32 w/ NTFS 2TB (possibly larger)
MacOS X w/ HFS+ 2TB
Explain normalization concept?
The normalization process involves getting our data to conform to three progressive normal forms, and a higher level of normalization cannot be achieved until the previous levels have been achieved (there are actually five normal forms, but the last two are mainly academic and will not be discussed).
First Normal Form
The First Normal Form (or 1NF) involves removal of redundant data from horizontal rows. We want to ensure that there is no duplication of data in a given row, and that every column stores the least amount of information possible (making the field atomic).
Second Normal Form
Where the First Normal Form deals with redundancy of data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data in vertical columns. As stated earlier, the normal forms are progressive, so to achieve Second Normal Form, your tables must already be in First Normal Form.
Third Normal Form
I have a confession to make; I do not often use Third Normal Form. In Third Normal Form we are looking for data in our tables that is not fully dependant on the primary key, but dependant on another value in the table
What’s the difference between accessing a class method via -> and via ::?
:: is allowed to access methods that can perform static operations, i.e. those, which do not require object initialization.
What are the advantages and disadvantages of CASCADE STYLE SHEETS?
External Style Sheets
Advantages
Can control styles for multiple documents at once Classes can be created for use on multiple HTML element types in many documents Selector and grouping methods can be used to apply styles under complex contexts
Disadvantages
An extra download is required to import style information for each document The rendering of the document may be delayed until the external style sheet is loaded Becomes slightly unwieldy for small quantities of style definitions
Embedded Style Sheets
Advantages
Classes can be created for use on multiple tag types in the document Selector and grouping methods can be used to apply styles under complex contexts No additional downloads necessary to receive style information
Disadvantage
This method can not control styles for multiple documents at once
Inline Styles
Advantages
Useful for small quantities of style definitions Can override other style specification methods at the local level so only exceptions need to be listed in conjunction with other style methods
Disadvantages
Does not distance style information from content (a main goal of SGML/HTML) Can not control styles for multiple documents at once Author can not create or control classes of elements to control multiple element types within the document Selector grouping methods can not be used to create complex element addressing scenarios
What type of inheritance that php supports?
In PHP an extended class is always dependent on a single base class, that is, multiple inheritance is not supported. Classes are extended using the keyword ‘extends’.
How can increase the performance of MySQL select query?
We can use LIMIT to stop MySql for further search in table after we have received our required no. of records, also we can use LEFT JOIN or RIGHT JOIN instead of full join in cases we have related data in two or more tables.
How can we change the name of a column of a table?
MySQL query to rename table: RENAME TABLE tbl_name TO new_tbl_name
or,
ALTER TABLE tableName CHANGE OldName newName.
When you want to show some part of a text displayed on an HTML page in red font color? What different possibilities are there to do this? What are the advantages/disadvantages of these methods?
There are 2 ways to show some part of a text in red:
1. Using HTML tag <font color=”red”>
2. Using HTML tag <span style=”color: red”>
When viewing an HTML page in a Browser, the Browser often keeps this page in its cache. What can be possible advantages/disadvantages of page caching? How can you prevent caching of a certain page (please give several alternate solutions)?
When you use the metatag in the header section at the beginning of an HTML Web page, the Web page may still be cached in the Temporary Internet Files folder.
A page that Internet Explorer is browsing is not cached until half of the 64 KB buffer is filled. Usually, metatags are inserted in the header section of an HTML document, which appears at the beginning of the document. When the HTML code is parsed, it is read from top to bottom. When the metatag is read, Internet Explorer looks for the existence of the page in cache at that exact moment. If it is there, it is removed. To properly prevent the Web page from appearing in the cache, place another header section at the end of the HTML document. For example:
What are the different ways to login to a remote server? Explain the means, advantages and disadvantages?
There is at least 3 ways to logon to a remote server:
Use ssh or telnet if you concern with security
You can also use rlogin to logon to a remote server.
Please give a regular expression (preferably Perl/PREG style), which can be used to identify the URL from within a HTML link tag.
Try this: /href=”([^”]*)”/i
How can I use the COM components in php?
The COM class provides a framework to integrate (D)COM components into your PHP scripts.
string COM::COM( string module_name [, string server_name [, int codepage]]) – COM class constructor.
Parameters:
module_name: name or class-id of the requested component.
server_name: name of the DCOM server from which the component should be fetched. If NULL, localhost is assumed. To allow DCOM com, allow_dcom has to be set to TRUE in php.ini.
codepage – specifies the codepage that is used to convert php-strings to unicode-strings and vice versa. Possible values are CP_ACP, CP_MACCP, CP_OEMCP, CP_SYMBOL, CP_THREAD_ACP, CP_UTF7 and CP_UTF8.
Usage:
$word->Visible = 1; //open an empty document
$word->Documents->Add(); //do some weird stuff
$word->Selection->TypeText(“This is a test…”);
$word->Documents[1]->SaveAs(“Useless test.doc”); //closing word
$word->Quit(); //free the object
$word->Release();
$word = null;
How many ways we can give the output to a browser?
HTML output
PHP, ASP, JSP, Servlet Function
Script Language output Function
Different Type of embedded Package to output to a browser
What is the default session time in php and how can I change it?
The default session time in php is until closing of browser
What changes I have to do in php.ini file for file uploading?
Make the following line uncomment like:
; Whether to allow HTTP file uploads.
file_uploads = On
; Temporary directory for HTTP uploaded files (will use system default if not
; specified).
upload_tmp_dir = C:\apache2triad\temp
; Maximum allowed size for uploaded files.
upload_max_filesize = 2M
How can I set a cron and how can I execute it in Unix, Linux, and windows?
Cron is very simply a Linux module that allows you to run commands at predetermined times or intervals. In Windows, it’s called Scheduled Tasks. The name Cron is in fact derived from the same word from which we get the word chronology, which means order of time.
The easiest way to use crontab is via the crontab command.
# crontab
This command ‘edits’ the crontab. Upon employing this command, you will be able to enter the commands that you wish to run. My version of
Linux uses the text editor vi. You can find information on using vi here.
The syntax of this file is very important – if you get it wrong, your crontab will not function properly. The syntax of the file should be as follows:
minutes hours day_of_month month day_of_week command
All the variables, with the exception of the command itself, are numerical constants. In addition to an asterisk (*), which is a wildcard that allows any value, the ranges permitted for each field are as follows:
Minutes: 0-59
Hours: 0-23
Day_of_month: 1-31
Month: 1-12
Weekday: 0-6
We can also include multiple values for each entry, simply by separating each value with a comma.
command can be any shell command and, as we will see momentarily, can also be used to execute a Web document such as a PHP file.
So, if we want to run a script every Tuesday morning at 8:15 AM, our mycronjob file will contain the following content on a single line:
15 8 * * 2 /path/to/scriptname
This all seems simple enough, right? Not so fast! If you try to run a PHP script in this manner, nothing will happen (barring very special configurations that have PHP compiled as an executable, as opposed to an Apache module). The reason is that, in order for PHP to be parsed, it needs to be passed through Apache. In other words, the page needs to be called via a browser or other means of retrieving
Web content. For our purposes, I’ll assume that your server configuration includes wget, as is the case with most default configurations. To test your configuration, log in to shell. If you’re using an RPM-based system (e.g. Redhat or Mandrake), type the following:
# wget help
If you are greeted with a wget package identification, it is installed in your system.
You could execute the PHP by invoking wget on the URL to the page, like so:
# wget http://www.example.com/file.php
Now, let’s go back to the mailstock.php file we created in the first part of this article. We saved it in our document root, so it should be accessible via the Internet. Remember that we wanted it to run at 4PM Eastern time, and send you your precious closing bell report? Since I’m located in the Eastern timezone, we can go ahead and set up our crontab to use 4:00, but if you live elsewhere, you might have to compensate for the time difference when setting this value.
This is what my crontab will look like:
0 4 * * 1,2,3,4,5 wget http://www.example.com/mailstock.php
Steps for the payment gateway processing?
An online payment gateway is the interface between your merchant account and your Web site. The online payment gateway allows you to immediately verify credit card transactions and authorize funds on a customer’s credit card directly from your Web site. It then passes the transaction off to your merchant bank for processing, commonly referred to as transaction batching
How many ways I can redirect a PHP page?
Here are the possible ways of php page redirection.
1. Using Java script:
‘; echo ‘window.location.href=”‘.$filename.'”;’; echo ”; echo ”; echo ”; echo ”; } } redirect(‘http://maosjb.com’); ?>
2. Using php function: header(“Location:http://maosjb.com “);
List out different arguments in PHP header function?
void header ( string string [, bool replace [, int http_response_code]])
What type of headers have to be added in the mail function to attach a file?
$boundary = ‘–‘ . md5( uniqid ( rand() ) );
$headers = “From: \”Me\”\n”;
$headers .= “MIME-Version: 1.0\n”;
$headers .= “Content-Type: multipart/mixed; boundary=\”$boundary\””;
How to store the uploaded file to the final location?
move_uploaded_file ( string filename, string destination)
This function checks to ensure that the file designated by filename is a valid upload file (meaning that it was uploaded via PHP’s HTTP POST upload mechanism). If the file is valid, it will be moved to the filename given by destination.
If filename is not a valid upload file, then no action will occur, and move_uploaded_file() will return FALSE.
If filename is a valid upload file, but cannot be moved for some reason, no action will occur, and move_uploaded_file() will return FALSE. Additionally, a warning will be issued.
What is the difference between Reply-to and Return-path in the headers of a mail function?
Reply-to: Reply-to is where to delivery the reply of the mail.
Return-path: Return path is when there is a mail delivery failure occurs then where to delivery the failure notification.
Explain about Type Juggling in php?
PHP does not require (or support) explicit type definition in variable declaration; a variable’s type is determined by the context in which that variable is used. That is to say, if you assign a string value to variable $var, $var becomes a string. If you then assign an integer value to $var, it becomes an integer.
An example of PHP’s automatic type conversion is the addition operator ‘+’. If any of the operands is a float, then all operands are evaluated as floats, and the result will be a float. Otherwise, the operands will be interpreted as integers, and the result will also be an integer. Note that this does NOT change the types of the operands themselves; the only change is in how the operands are evaluated.
$foo += 2; // $foo is now an integer (2)
$foo = $foo + 1.3; // $foo is now a float (3.3)
$foo = 5 + “10 Little Piggies”; // $foo is integer (15)
$foo = 5 + “10 Small Pigs”; // $foo is integer (15)
If the last two examples above seem odd, see String conversion to numbers.
If you wish to change the type of a variable, see settype().
If you would like to test any of the examples in this section, you can use the var_dump() function.
Note: The behavior of an automatic conversion to array is currently undefined.
Since PHP (for historical reasons) supports indexing into strings via offsets using the same syntax as array indexing, the example above leads to a problem: should $a become an array with its first element being “f”, or should “f” become the first character of the string $a? The current versions of PHP interpret the second assignment as a string offset identification, so $a becomes “f”, the result of this automatic conversion however should be considered undefined. PHP 4 introduced the new curly bracket syntax to access characters in string, use this syntax instead of the one presented above:
How can I embed a java programme in php file and what changes have to be done in php.ini file?
There are two possible ways to bridge PHP and Java: you can either integrate PHP into a Java Servlet environment, which is the more stable and efficient solution, or integrate Java support into PHP. The former is provided by a SAPI module that interfaces with the Servlet server, the latter by this Java extension.
The Java extension provides a simple and effective means for creating and invoking methods on Java objects from PHP. The JVM is created using JNI, and everything runs in-process.
Example Code:
getProperty(‘java.version’) . ”; echo ‘Java vendor=’ . $system->getProperty(‘java.vendor’) . ”; echo ‘OS=’ . $system->getProperty(‘os.name’) . ‘ ‘ . $system->getProperty(‘os.version’) . ‘ on ‘ . $system->getProperty(‘os.arch’) . ‘ ‘; // java.util.Date example $formatter = new Java(‘java.text.SimpleDateFormat’, “EEEE, MMMM dd, yyyy ‘at’ h:mm:ss a zzzz”); echo $formatter->format(new Java(‘java.util.Date’)); ?>
The behaviour of these functions is affected by settings in php.ini.
Table 1. Java configuration options
Name
Default
Changeable
java.class.path
NULL
PHP_INI_ALL
Name Default Changeable
java.home
NULL
PHP_INI_ALL
java.library.path
NULL
PHP_INI_ALL
java.library
JAVALIB
PHP_INI_ALL
How To Turn On the Session Support?
The session support can be turned on automatically at the site level, or manually in each PHP page script:

  • Turning on session support automatically at the site level: Set session.auto_start = 1 in php.ini.
  • Turning on session support manually in each page script: Call session_start() funtion.

Explain the ternary conditional operator in PHP?
Expression preceding the ? is evaluated, if it’s true, then the expression preceding the : is executed, otherwise, the expression following : is executed.
What’s the difference between include and require?
It’s how they handle failures. If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.
How many ways can we get the value of current session id?
session_id() returns the session id for the current session.
How can we destroy the cookie?
Set the cookie in past.
How To Read the Entire File into a Single String?
If you have a file, and you want to read the entire file into a single string, you can use the file_get_contents() function. It opens the specified file, reads all characters in the file, and returns them in a single string. Here is a PHP script example on how to file_get_contents():
<?php
$file = file_get_contents(“/windows/system32/drivers/etc/services”);
print(“Size of the file: “.strlen($file).”\n”);
?>
This script will print:
Size of the file: 7116


Categories
LAMP MySQL PHP

PHP Advanced Questions and Answers part one

PHP Advanced Questions and Answers part one :


1.Is it possible to set a time expire page in PHP.?

Yes it is

Using header(“Expires: fri, 07 mar 2007 05:00:00 GMT”);

<?php
header(“Expires: fri, 07 mar 2007 05:00:00 GMT”);
?>

2.How can we SAVE an image from a remote
web Server to my web server using PHP?

<?php
$file_rimg = fopen(“http://w3answers /image23.jpg”,’rb’);
$newfile_name_img = “/tmp/tutorial.file”;
$file_wnew = fopen($newfile_name_img,’wb’);
while (!feof($file_rimg)) {
$chunk_rd = fread($file_rimg,1024);
fwrite($file_wnew,$chunk_rd);
}
fclose($file_wnew);
fclose(file_rimg);
?>
3.What is the output of 2^2 in php ?

The answer is 0 (Zero)
Important note
Everyone expected answer would be 4.   But answer is zero.  How it happened only in php ?

The ^ operator is different in each language.In PHP ^ means the bitwise exlusive or of the two numbers.

4.What is the output of below script?

<?php
$x = 3;
switch ($x) {
case 2: echo ‘line 1’; break;
case 3:
case 4: echo ‘line 2’; break;
default: echo ‘line 3’;
}
?>

a. echo ‘line 3’;
b. echo ‘line 2’;
c. Error
d. None of the above

Ans: b (Answer is line2)
5.What is the output here?

<?php
$x = ‘raj’;
echo ‘Hello $x’;

?>

a. helloravj
b. Parse error
c. hello $x
d. syntax error

ANS: c

6.What output do you get here?

<?php
$list = array(“block”,”cut”,”pens”,”dogs”);
$list[] = “elephant”;
$list[] = “dragon”;
print “$list[4]”;
?>

a. Error
b. elephant
c. dragon
d. nothing
e. dogs

ANS: b (elephant)

7.what is the output for following code?

<?php
echo 12+FALSE;
?>

a. 12
b. no
c. parse error
d. T_ECHO error
e. FALSE

ANS: 12

8.What is the output ?

<?php
$x=7;
if ($x < 2) { echo “11”; }
elseif ($x < 16) { echo “12”; }
elseif ($x < 14) { echo “13”; }
elseif ($x > 14) { echo “14”; }
elseif ($x < 10) { echo “15”; }
else { echo “16”; }

?>

a.16
b.15
c.12
d.13

ANS:12

9.What is the result here?

<?php
echo “test”;
$x = ”;
switch ($x) {
case “0”: echo “String”; br;
case 0: echo “”; break;
case NULL: echo “NULL”; br;
case FALSE: echo “integer”; br;
case “”: echo “no string”; br;
default: echo “nothing else”; br;
}

?>

a. Something else
b. Empty string
c. Integer
d. String

ANS: Integer

10.What is the output?

<?php
function x ($y) {
function y ($z) {
return ($z*2); }
return($y+3); }
$y = 4;
$y = x($y)*y($y);
echo “$y”;
?>

a. None
b. 54
c. 56
d. 58

ANS:56

 

source: w3answers.com