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PHP: PHP Hypertext Preprocessor

PHP is a server-side scripting language where the code is executed in the server. Other server-side programming languages include ASP, JSP etc.

UNIT V CONTENTS

UNIT VI CONTENTS

PHP Introduction

PHP stands for PHP: Hypertext Preprocessor.
It is a server side scripting language like ASP, JSP and the scripts run in the server.
PHP is an open source software and is free to download and use.
It is compatible with many databases such as MySQL, Oracle, Sybase, and other popular DBMS.
PHP runs on all platforms (Linux, Windows etc) and is compatible with almost all servers used today (Apache, IIS, etc).
It is easy to learn and runs really efficient on the server side.
PHP code can be embedded in the HTML code like javascript.
Extension of PHP files can be .php, .php3 or .phtml

Creating & Running PHP Script

PHP is a server-side scripting language. So, to run PHP scripts, you need to install PHP and a web-server software like Apache. For scripting using databases, a DBMS such as MySQL should be installed.
The most compatible options include PHP + Apache + MySQL.
The PHP files (.php files) should be copied to a particular folder (htdocs or html or www etc.) where the webpages need to be hosted.
The basic syntax of a PHP code is as follows:

<HTML>
<BODY>

<?php
echo "Hello VIT!";
?>

</BODY>
</HTML>
After copying the files to the server, you can type the ip of the system followed by the php page in the URL bar of the browser . For example, http://192.169.1.112/test.php. To access the PHP page in the same system use, http://localhost/test.php
Each statement in PHP ends with a semicolon (;).
To output text or result to the screen in PHP, echo or print can be used. Example, print "Hello";
Comments in PHP is similar to that of Javascript. For single line, // can be used. For multiline comments, /* and */ can be used.

PHP Variables & Constants

PHP variables start with $. For example, $name = "Suresh Mudunuri", $i=55 etc.
More Information on PHP Variables can be found @
- http://www.tizag.com/phpT/variable.php
- http://www.w3schools.com/php/php_variables.asp
Constants are variables whose values can not be changed. Constants in PHP can be created using the define statement. Example, define(PI, 3.14); echo PI; - This statement will print 3.14

PHP Data Types

PHP supports data types that are similar to JavaScript. But, broadly they can be categorized to 3 types - Numeric, String and Array.
Numeric: PHP variables can hold data of all types of numbers like integers, floating point values etc.
Strings: Strings are used for holding characters and text.

Arrays: Arrays store multiple values in a single varaible. PHP Arrays are of 3 types - Numeric, Associative (ID, Key pairs) and Multi-Dimensional Arrays.
Information about the PHP data types can be found @
- Strings: http://www.w3schools.com/php/php_string.asp
- Built-in Functions of PHP Strings: http://www.w3schools.com/php/php_ref_string.asp
- Arrays: http://www.w3schools.com/php/php_arrays.asp
- Built-in Functions of PHP Arrays: http://www.w3schools.com/php/php_ref_array.asp

PHP OPERATORS

PHP supports The following operators:
- Arithmetic (+, -, *, /, %, .)
- Assignment (=, +=, *=, .=, etc.,)
- Increment/Decrement (++, --)
- Relational (==, >, <, <=, >=, !=) Special:===, !==, <> (Not equal to)
- Logical (&&, ||, !) Alternates:and (&&), or (||)
- Array Operators: + (union), == (equality), === (identity), != / <>(inequality), !== (non-identity)
More information about PHP operators can be found @
- Operators: http://www.w3schools.com/php/php_operators.asp

PHP Conditional & Control Statements

PHP supports The following conditional statements:
- If statement
- If-else statement
- If-elseif-else statement
- Switch statement
- While Loop
- Do-While Loop
- For Loop
- For-Each Loop
Information about the usage of PHP Coniditonal Statements can be found @
- If-esle statements: http://www.w3schools.com/php/php_if_else.asp
- Switch statement: http://www.w3schools.com/php/php_switch.asp
- While & Do-while Loops: http://www.w3schools.com/php/php_looping.asp
- For & For-each Loops: http://www.w3schools.com/php/php_looping_for.asp

PHP Functions

Functions are the real power for PHP. There are as many as 700 built in functions in PHP.
You may call a function from anywhere within a page.
Usage of PHP functions with arguments and return statements ia almost similar to that of javascript functions.
The basic syntax of a PHP code is as follows:

<?php

function add()
{
echo "Hello VIT!";
}

add();//function call
?>
Information about PHP functions can be found @
- PHP Functions: http://www.w3schools.com/php/php_functions.asp
- PHP Functions Reference: http://www.w3schools.com/php/default.asp