I would like to share my personal experience and challenges which i have faced during working on different different browser for an application.
here are the some challenges in key points:

1.Display box in IE & other browser

Solution:
For IE:-

#box{ display:inline; border: solid 1px; }

For Other browser:-
#box {
display: inline-block;
border: solid 1px;
}

2.Anchor tag (hyperlink) visited issue

Html code :

tesing hyperlink

a:link {
color: #A5ACB0;
}
/* visited link */
a:visited {
color: #00ADEF;
}
/* selected or active link */
a:active {
color: #A5ACB0;
}
/* Hover link */
a:hover {
color: #00338E;
}

Test IE
Test ALL

For IE Broswer:-
After clicking on TestIE link , it will show a:visited color but when you go to other page and come back to the same page where you have TestIE link , the color of hyperlink will as a:link .
Logically , it should be a:visited color because you have visited the link.
This logic won’t work on IE 6,7,8 and other latest IE versions but work perfectly fine on any other browsers.

But After clicking on TestALL link on any browser, it shows visited color .

images:- top_arrow_disable.jpg , top_arrow_active.jpg and top_arrow_visited.jpg

What is  PDO ?

• Its written in complied language(c/c++) , other php libraries are written in Interpreted language (AdoDB , PEAR DB)
• its lightweight database connection abstraction library

WHY PDO ?

• It support many databases , so you don’t need to write lines of code of each database , just write one code and run on any database
• Speed . PDO is written in complied language but others php libraries like PEAR DB ,Adodb are written in interpreted language.

PHP supports many databases like mysql , sqllite , postgre sql etc.

mysql_connect($host,$user,$password)

sqllite_open($host,$user,$password)

pg_connect($host,$user,$password)

so if you have to change your database from say mysql to postgre or viceversa , then you have to change your code , so you have to do rework on that.

thats way PDO cam ein picture , so that you have to write just one code and it will be work on any database platform without changing codes again and again.

PDO: Activation PHP Data Objects Extension

Goto PHP/ext folder and check whether pdo extension exists or not.

php_pdo.dll , php_pdo_mysql.dll etc.

To enable PDO , go to PHP.INI file and uncommnet the code

;extension=php_pdo.dll -> extension=php_pdo.dll

;extension=php_mysql_pdo.dll -> extension=php_mysql_pdo.dll

Restart your apache server.

PDO: connection to databases

//mysql connection

$con = new PDO(‘mysql:host=$host,dbname=$DB’,$user,$pwd);

//sqllite connection

$con = new PDO(‘sqllite:$DB’);

//postgre connection

$con = new PDO(‘pqsql:host=$host,dbname=$DB’,$user,$pwd);

or we can write like this also

<?php
// configuration
$dbtype		= "sqlite";
$dbhost 	= "localhost";
$dbname		= "test";
$dbuser		= "root";
$dbpass		= "admin";
$dbpath		= "c:/test.db";

// switching
switch($dbtype){
  case "mysql":
    $dbconn = "mysql:host=$dbhost;dbname=$dbname";
    break;

  case "sqlite":
    $dbconn = "sqlite:$dbpath";
	break;

  case "postgresql":
    $dbconn = "pgsql:host=$host dbname=$db";
	break;
}

// database connection
$conn = new PDO($dbconn,$user,$pass);

?>

PDO: Fetch Mode

// database connection
$conn = new PDO("mysql:host=$dbhost;dbname=$dbname",$dbuser,$dbpass);

// query
$sql = "SELECT title FROM books ORDER BY title";
$q	 = $conn->query($sql);

// fetch
while($r = $q->fetch()){
  print_r($r);
}

// result //Array ( [title] => PHP AJAX [0] => PHP AJAX )


// query
$sql = "SELECT title FROM books ORDER BY title";
$q	 = $conn->query($sql);
$q->setFetchMode(PDO::FETCH_ASSOC); //fetch association 
// fetch
while($r = $q->fetch()){
  print_r($r);
}

// result //Array ( [title] => PHP AJAX)


$q->setFetchMode(PDO::FETCH_NUM);

// fetch
while($r = $q->fetch()){
  print_r($r);
}

// result //Array ( [0] => PHP AJAX )
$q->setFetchMode(PDO::FETCH_BOTH);
$q	 = $conn->query($sql);

// fetch
while($r = $q->fetch()){
  print_r($r);
}

// result //Array ( [title] => PHP AJAX [0] => PHP AJAX ) 

1. Data (Node, ETC)
2. Modules
3. Blocks and Menus
4. User Permissions
5. Template

Data
Base of the system is collection of Nodes. – the data pool

Modules
These are functional plugins that are either part of the Drupal core (they ship with Drupal) or they are contributed items that have been created by members of the Drupal community.

Blocks and Menus
This is the next layer where we find blocks and menus. Blocks often provide the output from a module or can be created to display whatever you want, and then can be placed in various spots in your template (theme) layout. Blocks can be configured to output in various ways, as well as only showing on certain defined pages, or only for certain defined users.

User Permissions
Here is the next layer where settings are configured to determine what different kinds of users are allow to work and see.

Template
This is mainly the site theme or the skin. This is made up predominantly of XHTML and CSS, with some PHP variables intermixed

Understanding this flow of information is very important if you are facing A Drupal project targeted interview as the interviewer might test your overall knowledge  of  Drupal CMS by asking this sort of questions.

What is taxonomy in drupal?

We can define any number of vocabularies (category types) and terms (categories)
e.g.
Controversial Content: (vocabulary)
– violence (term)
– adult content (term)

Genre (Vocabulary)
– Comedy (term)
– Romance (term)

We can config which content types are compatible with which vocabulary and which nodes are belong to which terms.

Some important drupal modules: Views, CCK, Path auto, FCK Editor, User points, Flags, Panels, Image cache

What is a block?

Block is a section in a page (recent posts, news, vote to something, login box, navigation), which is movable to regions (header, footer, content top etc) in a page. Blocks can be configured to show/hide only to certain type of user roles, url patterns or some other advanced criteria. (Content area is not a block)

What is a node in Drupal?

A node is a unit of content. It has a type. Page, News or as Testimonial.

Which are the core required modules in drupal 6.x ?

1. Block — Controls the boxes that are displayed around the main content.
2. Filter — Handles the filtering of content in preparation for display.
3. Node — Allows content to be submitted to the site and displayed on pages.
4. System — Handles general site configuration for administrators.
5. User — Manages the user registration and login system.

Drupal Modules

These key modules are some of the most important ones to add no matter what type of site you want to build with Drupal.

• Mollom for spam protection
• PathAuto for configurable automated URLs

We need  TOKEN module http://drupal.org/project/token

• FCKEditor for WYSIWYG post editing [download FCK Editor from this link http://sourceforge.net/projects/fckeditor/files/FCKeditor/2.6.6/FCKeditor_2.6.6.zip/download ]

Download FCKEDitor from sourcrforge and unzip it.

Place this unzip FCKEditor folder inside sites/aa/modules/FCKEditor .

There will be another folder as FCKEditor in FCKedior module folder ,copy the unzip from above link and copy here .

• IMCE for uploading images to insert into posts
• Poor Mans Cron for easy execution of the Drupal cron file

What is VIEW Module ?

VIEW is a powerful query builder for Drupal that allows you to fetch and present lists and tables of content (posts/nodes) to the user in ways that are tailored to your site and your content.

The Views module provides a flexible method for Drupal site designers to control how lists and tables of content (nodes in Views 1, almost anything in Views 2) are presented. Views can be used to generate reports, create summaries, and display collections of images and other content.

You need Views if:

• You like the default front page view, but you find you want to sort it differently.
• You like the default taxonomy/term view, but you find you want to sort it differently; for example, alphabetically.
• You use /tracker, but you want to restrict it to posts of a certain type.
• You like the idea of the ‘article’ module, but it doesn’t display articles the way you like.
• You want a way to display a block with the 5 most recent posts of some particular type.
• You want to provide ‘unread forum posts’.
• You want a monthly archive similar to the typical Movable Type/Wordpress archives that displays a link to the in the form of “Month, YYYY (X)” where X is the number of posts that month, and displays them in a block. The links lead to a simple list of posts for that month.

These two js files jquery.js , jquery.validate.js is very useful when user wants to do validation of form on client side server .

Here the attached code.just download these two js files from JQUERY site and embedd in below code and run the file on browser .

<html>
<head>
<title>jQuery Tutorial Demo: Select All Checkboxes</title>
<script type=”text/javascript” src=”/jquery/jquery.js”></script>
<script type=”text/javascript” src=”/jquery/jquery.validate.js”></script>
<style type=”text/css”>body{font-family:Verdana, Arial, Helvetica, sans-serif; font-size:11px}
h1, h2{font-size:20px;}</style>

<script type=”text/javascript”>
$(document).ready(function()
{
$(“#paradigm_all”).click(function()
{
var checked_status = this.checked;
$(“input[name=paradigm[]]”).each(function()
{
this.checked = checked_status;
});
});
});

//initiate validator on load
$(function() {
// validate contact form on keyup and submit
$(“#userForm”).validate({
//set the rules for the field names
rules: {
first_name: {
required: true,
minlength: 2
},
last_name: {
required: true,
minlength: 2
},
email: {
required: true,
email: true
},
company: {
required: true,
minlength: 2
},
},
//set messages to appear inline
messages: {
first_name: “*Please enter First Name”,
last_name: “*Please enter Last Name”,
email: “*Please enter a valid Email address”,
company: “*Please enter Company Name”
}
});
});

</script>
<style type=”text/css”>
.error {
color: red;
font: 12pt verdana;
padding-left: 10px
}
</style>
</head>
<body>

<h1>jQuery Tutorial: Multiple Checkbox values & Validation of FORM </h1>
<p>You will learn how to select/deselect all checkbox and get all the values of checked box.<br/>
This will also teach you to validate your FORM using JQUERY validate.js.
</p>
<br/><br/>
<?php
if(isset($_POST) && !empty($_POST))
{
var_dump($_POST);
}
?>
<form name=”myform” action =”#” id=”userForm” method=’post’ enctype=’multipart/form-data’>
<label for=”first_name”>First Name</label><br />
<input name=”first_name” id=”first_name” /><br />
<label for=”last_name”>Last Name</label><br />
<input name=”last_name” id=”last_name” /><br />
<label for=”email”>Email address/Username</label><br />
<input name=”email” id=”email” /><br />
<label for=”company”>Company</label><br />
<input name=”company” id=”company” /><br /><br />
<label>Role</label><br/>
<input type=”checkbox” name=”paradigm[]” value=”Imperative”>Imperative<br/>
<input type=”checkbox” name=”paradigm[]” value=”Object-Oriented”>Object-Oriented<br/>
<input type=”checkbox” name=”paradigm[]” value=”Functional”>Functional<br/>
<input type=”checkbox” id=”paradigm_all”>Select All<br><br />
<input type=”submit”  value=”save” />

</body>
</html>

1.UNZIP  Drupal-6.15 and rename folder drupal-6.1.5 to drupal and copy that in your server webroot
I am using XAMPP , so I kept this “drupal”  folder in “htdocs” folder
Start your Xampp server.
On browser , type:-

http://localhost/drupal

it will show this page as in screenshot
2.Follow drupal instructions
Choose language to English

3. After that you will get this screen

4.You will get screen like below and enter your DB name and all , after that click on ” SAVE AND CONTIUNE “ button

5. After that you will see screen as shown below .
This prompt error message because we don’t have “drupal_team”  database in MYSQL DB

 First create “drupal_team” db in MYSQL database
As  shown in screenshot

After creating DB name in MYSQL

6.Goto drupal installation browser
 
NOTE:- if u want then put prefix for your tables in “drupal_team” database. Its optional
See screenshot:-

7. after that we will see screen as shown and fill appropriate data .

8. AT last you will see screen as shown below , SMTP error will come but its just for mailing functionality which you can resolve in php.ini file.

This tutorial is about setting up Lightbox to work on your page.

STEP 1: download lightbox.js , lightbox.css ,prototype.js,scriptaculous.js,effects.js and builder.js

STEP 2: Create a folder ”launchpad” and ”js” , “css” and “image” sub folder inside ”launchpad” folder.

NOTE:- you can create a folder structure according to your wish also .

In “js” folder , keep all js files like:

lightbox.js ,prototype.js,scriptaculous.js,effects.js and builder.js

In “css” folder . keep lightbox.css file.

In “images” folder , keep all your images that you want to be displayed as photo gallery.

STEP 3: keep “lauchpad” folder inside C:\ drive

NOTE:- you can put this folder anywhere according to your wish but then you have to take care of Path of these folder.

STEP 4: Create lightbox.html page (you can rename your filename also.)

source code of lightbox.html :-

<html>
<head>
<title> Lightbox Example</title>
<link rel=”stylesheet” href=”c:/lightbox/css/lightbox.css” type=”text/css” media=”screen” />

// Lightbox.css :- for lightbox layout designing
<br/>
<script src=”c:/lightbox/js/prototype.js” type=”text/javascript”></script>
//prototype.js :-This will call to a needed Javascript file, ‘prototype.’ Without prototype, Lightbox WILL NOT function.
<br/>

<script src=”c:/lightbox/js/scriptaculous.js?load=effects,builder” type=”text/javascript”></script>

//scriptaculous.js :- Above statement  Not only  it calls to scriptaculous, but it will also call to effects.js and builder.js. Scriptaculous has a feature that will load the needed JS files with itself, hence the ?load after scriptaculous.js

<br/>

<script src=”c:/lightbox/js/lightbox.js” type=”text/javascript”></script>
//Lightbox.js

</head>
<body>
<h1>Light Box Example</h1>
<br/><br/>
<a href=”c:/lightbox/images/a.jpg” rel=”lightbox” title=”Gallery”>What is it?</a><br/><br/>

// The beauty of Lightbox is that you only need to call to it in link attributes, and not image attributes. <br/>
// rel=”lightbox” tells the webserver that the relation of this link is Lightbox, so, it will link Lightbox.js and all other JS files to the link. <br/>
// Title is optional, it will be displayed below the image<br/>
// Now, we’ll link some images together, commented code will be after so you understand.<br/>

<br/><br/>

<a href=”c:/lightbox/images/a.jpg” rel=”lightbox[outdoors]“>Gallery 1</a><br/>
<a href=”c:/lightbox/images/b.jpg” rel=”lightbox[outdoors]“>Gallery 2</a><br/>
<a href=”c:/lightbox/images/c.jpg” rel=”lightbox[outdoors]“>Gallery 3</a><br/>
<a href=”c:/lightbox/images/d.jpg” rel=”lightbox[outdoors]“>Gallery 4</a><br/>
<a href=”c:/lightbox/images/e.jpg” rel=”lightbox[outdoors]“>Gallery 5</a><br/>
<br/><br/>
//Everything is the same as above, except that we’ve added within brackets the word ‘outdoors.’ Outdoors links those five images together so that we will get ‘Next’ and/or ‘Previous’ linkings within Lightbox.
</body>
</html>

copy and paste this code into lightbox.html file

NOTE: -

<a href=”c:/lightbox/images/a.jpg” rel=”lightbox[outdoors]“>Gallery 1</a><br/>
<a href=”c:/lightbox/images/b.jpg” rel=”lightbox[outdoors]“>Gallery 2</a><br/>
<a href=”c:/lightbox/images/c.jpg” rel=”lightbox[outdoors]“>Gallery 3</a><br/>
<a href=”c:/lightbox/images/d.jpg” rel=”lightbox[outdoors]“>Gallery 4</a><br/>
<a href=”c:/lightbox/images/e.jpg” rel=”lightbox[outdoors]“>Gallery 5</a><br/>

In the above code ,

you   can rename your image name as well as you can use “n”  number of images that has to be displayed.

suppose , i can add other statement in above code,like this

<a href=”c:/lightbox/images/hello.jpg” rel=”lightbox[outdoors]“>Gallery 6</a>

STEP 5: In lightbox.css,

change  path of images for these attributes

fileLoadingImage:        ‘c:/lightbox/images/loading.gif’,     
 fileBottomNavCloseImage: ‘c:/lightbox/images/closelabel.gif’,

STEP 6: run lightbox.html page and click on  any of links to see lightbox effects .

1.Why magic methods ?

Ans:

In PHP,  a variable can take any form depending on the data passed to it. Also PHP automatically creates variable and assigns values to it even if the variables are not defined. But in Object Oriented Programming all the data members/methods needs to be defined. To solve some of these problems in OOPS environment magic methods have been introduced in PHP5.

1. Magic methods are member function that is available for all instance of class.
2. Magic method stars with __(double underscore), like: __get () ,__set()
3. Magic methods are always declared as PUBLIC.

LIST of MAGIC METHODS used in PHP 5 :

__get() , __set() , __autoload , __sleep() , __wakeup() , __construct() , __destruct() , __isset() , __unset() , __clone , __call ,__toString()

1. __construct() :- This methods gets called whenever an object of a class is instantiated.

2. __destruct() :-  This methods gets called whenever an object of a class is destroyed or object goes out of scope.

3. __set() :-  This methods get automatically called whenever you assigns data to a undefined attributes of an class in PHP 5. With this method the programmer can keep track on the variables which are not defined inside the class.

Syntax:

< ?

function __set($data,$value){

//$data – holds the name of the undefined attributes

//$value – holds the value assigned to the undefined attributes.

}

?>

Example:

< ?
class magicmethod{
               function __set($data,$value)
               {
                               echo "Error assigning values to undefined attributes";
                               echo "attributes Called:".$data;
                               echo "Value assigned to attributes:".$value;
               } 
}
$a = new magicmethod();
$a->setData = 20;
?>
In Above example : 

Output:
Error assigning values to undefined attributes
attributes Called:setData
Value assigned to attributes:20

Explain:

In the magicmethod class setData is not defined so the php compiler excutes __set() magic method and displays error message.

And  assigned value 20 to an attribute setData of magicmethod class.

5. __get() :- This methods get automatically called when you try to retrieves the data of undefined attributes of an class in PHP 5.

Syntax:

function __get($data)
{
     //$data holds the name of the undefined attributes getting called.
}
  
Example:
< ?
class magicmethod
{
   function __get($data)
   {
       echo "Error accessing undefined attributes";
       echo "attributes Called:".$data;
   }
}
 
$a = new magicmethod();
echo $a->setData;
 
?>
 
Output:
Error accessing undefined attributes
attributes Called:setData
 
Explain: 
a.echo an attribute setData of magicmethod class.
b.But in the magicmethod class setData is not defined so the php compiler excutes __get() magic method and displays error message 

6.__cal() :- The __call Magic method in PHP5 get called when accessing an undeclared or undefined methods of an class. With this magic method the programmer can keep track on the undeclared method which are not defined inside the class.

Syntax:

< ?
function __call($data,$argument)
{
               //$data holds the name of the undefined method getting called.
        //$argument holds the argument passed to the method.
}
?>

Example:

< ?
class magicmethod
{
 
               function __call($data,$argument)
               {
                               echo "Error accessing undefined Method";
                               echo "Method Called: ".$data;
                               echo "Argument passed to the Method: ".$argument;
               }
 
}
 
$a = new magicmethod();
echo $a->setData();  //Calling setData method
 
?>

Output:
Error accessing undefined Method
Method Called: setData
Argument passed to the Method: Array (Array of the Argument Passed)

Explain:

1.trying to call setData method of magicmethod class.

2.Now in the magicmethod class setData is not defined so the php compiler excutes __call() magic method and displays error message.

6. __sleep() :-  This methods gets called when you serialize the object in PHP 5. Serializing is required to pass complex data across the network or PHP pages. It is also used to store data(files, database, cookies etc).

Syntax:

< ?
function __sleep()
{
               ...
               return serialised data;
}
?>

Example:

< ?
class magicmethod
{
               function __sleep()
               {
                               echo "Performing Clean-Up Operation Before Serializing Data ";
                               return array("Serialized Data","1","2","3");
               }
}
$a = new magicmethod();
$serializedata = serialize($a);
echo $serializedata;
?>

Output:
Performing Clean-Up Operation Before Serializing Data O:11:”magicmethod”:4:{s:15:”Serialized Data”;N;s:1:”1″;N;s:1:”2″;N;s:1:”3″;N;}

Explain:

a.trying to serialize the object of magicmethod class.

b.Now the PHP Compiler calls the __sleep() Magic method which return an array having the serialized values

7.__wakeup() :- This methods gets called when the object is about to be unserialized in PHP 5. This method allows us to restore the serialized data to its normal form.

Syntax:

function __wakeup()
{
               ...
}

Example:

< ?
class magicmethod
{
               private $setName;
               function __sleep()
               {
                               echo "Performing Clean-Up Operation Before Serializing Data ";
                               $this->setName = "Hello World!!!";
                               return array(setName);
               }
 
               function __wakeup()
               {
                               echo "Performing Clean-Up Operation Before Unserializing Data ";
                               echo $this->setName;
               }
}
$a = new magicmethod();
$serializedata = serialize($a);
$serializedata1 = unserialize($serializedata);
?>

Output:
Performing Clean-Up Operation Before Serializing Data
Performing Clean-Up Operation Before Unserializing Data
Hello World!!!

Explain:

a.trying to serialize the object of magicmethod class

b.Now the PHP Compiler calls the __sleep method which return an array having the serialized values

c. After serialize data, i am calling the unserialize function; now the PHP compiler will call the __wakeup method which contains the original data that was serialized .

8. __autoload():-This methods get automatically called whenever you try to load an object of class which resides in separate file and you have not included those files using include,require and include_once. To use this method it is mandatory to the PHP filename as that of the class name because this methods accepts the class name as the argument.

Syntax:

< ?
   function __autoload($classname)
   {
      require($classname.".php");
   }
//$classname is the name of the Class.
?>

Example:

//magicmethod1.php

< ?
    class magicmethod1
    {
        function __construct()
        {
            echo "MagicMethod1 Class Called";
        }
    }
  ?>
<?php
    function __autoload($classname)
    {
        include $classname.".php"; //Here $classname=magicmethod1
    }
 
    $a = new magicmethod1();
?>

Output: MagicMethod1 Class Called

Explain:

trying to create an object of magicmethod1 class, but i have not included the magicmethod1.php so PHP compiler calls the __autoload() method which include that magicmethod1.php file.

9.__clone() :- PHP5 has introduced clone method which creates an duplicate copy of the object. __clone methods automatically get called whenever you try to call clone methods in PHP 5. This operator does not creates a reference copy.

In PHP 5 when you assign one object to another object creates a reference copy and does not create duplicate copy. This would create a big mess as all the object will share the same memory defined for the object. To counter this PHP 5 has introduced clone method

Example:

//without cloning

< ?
class Animal
{
   public $name;
   public $legs;
 
   function setName($name)
   {
               $this->name = $name;
   }
 
   function setLegs($legs)
   {
               $this->legs = $legs;
   }
}
 
$tiger = new Animal();
$tiger->name = "Tiger";
$tiger->legs = 4;
 
$kangaroo = $tiger;
$kangaroo->name = "Kangaroo";
$kangaroo->legs = 2;
 
echo $tiger->name."---".$tiger->legs;
echo "<br />".$kangaroo->name."---".$kangaroo->legs;
?>

Output:
Kangaroo—2
Kangaroo—2

Explanation:

• Here i have created an $tiger object of Animal class
• Created another variable $kangaroo and assigned $tiger to $kangaroo
• After echo it print the details entered last because both the variables are referring to the same memory location

Example:

//with __Clone

< ?
class Animal
{
   public $name  ;
   public $legs;
 
   function setName($name)
   {
               $this->name = $name;
   }
 
   function setLegs($legs)
   {
               $this->legs = $legs;
   }
 
   function __clone()
   {
               echo "<br />Object Cloning in Progress";
   }
}
 
$tiger = new Animal();
$tiger->name = "Tiger";
$tiger->legs = 4;
 
$kangaroo = clone $tiger;
$kangaroo->name = "Kangaroo";
$kangaroo->legs = 2;
 
echo "<br />".$tiger->name."---".$tiger->legs;
echo "<br />".$kangaroo->name."---".$kangaroo->legs;
?>

Output:
Object Cloning in Progress
Tiger—4
Kangaroo—2

Explanation:

• Here i have created an $tiger object of Animal class
• Created another variable $kangaroo having clone of $tiger. This calls the __clone magic method
• After echo it print the details entered by individual object as both of them are referring to separate object and memory location

The above technique of cloning discussed is called shallow copy. There are other techniques called Deep Copy wherein you create duplicate copy of objects referring to other objects etc.

10. __toString() :- __toString method is called when PHP needs to convert class instances into strings, for example when echoing:

<?php

class SomeClass {
public function __toString() {
return ‘someclass’;
}
}

$obj = new SomeClass();
echo $obj;
//will output ‘someclass’

?>

11. __isset() :- This methods get automatically called whenever you try to check the existence of the undeclared attributes of the class using isset function of PHP.

12. __unset() :- This methods get automatically called whenever you try to check the destroy or clear an undeclared attributes of the class using unset function of PHP