PHP Variables

Variables in PHP


Variables are used for storing a values, like text strings, numbers or arrays.

When a variable is declared, it can be used over and over again in your script.

All variables in PHP start with a $ sign symbol.

The correct way of declaring a variable in PHP:
----------------------------------------------------------
$var_name = value;
----------------------------------------------------------
New PHP programmers often forget the $ sign at the beginning of the variable. In that case it will not work.


Let's try creating a variable containing a string, and a variable containing a number:
----------------------------------------------------------


$txt="Hello World!";
$x=16;
?>
----------------------------------------------------------
PHP is a Loosely Typed Language


In PHP, a variable does not need to be declared before adding a value to it.
In the example above, you see that you do not have to tell PHP which data type the variable is.
PHP automatically converts the variable to the correct data type, depending on its value.
In a strongly typed programming language, you have to declare (define) the type and name of the variable before using it.
In PHP, the variable is declared automatically when you use it.
--------------------------------------------------------------------------------
Naming Rules for Variables

A variable name must start with a letter or an underscore "_"
A variable name can only contain alpha-numeric characters and underscores (a-z, A-Z, 0-9, and _ )
A variable name should not contain spaces. If a variable name is more than one word, it should be separated with an underscore ($my_string), or with capitalization ($myString)

PHP Syntax

PHP code is executed on the server, and the plain HTML result is sent to the browser.


--------------------------------------------------------------------------------

Basic PHP Syntax
A PHP scripting block always starts with . A PHP scripting block can be placed anywhere in the document.

On servers with shorthand support enabled you can start a scripting block with .

For maximum compatibility, we recommend that you use the standard form (

A PHP file normally contains HTML tags, just like an HTML file, and some PHP scripting code.

Below, we have an example of a simple PHP script which sends the text "Hello World" to the browser:









Each code line in PHP must end with a semicolon. The semicolon is a separator and is used to distinguish one set of instructions from another.

There are two basic statements to output text with PHP: echo and print. In the example above we have used the echo statement to output the text "Hello World".

Note: The file must have a .php extension. If the file has a .html extension, the PHP code will not be executed.


--------------------------------------------------------------------------------

Comments in PHP
In PHP, we use // to make a single-line comment or /* and */ to make a large comment block.

PHP Installation

What do you Need?


If your server supports PHP you don't need to do anything.



Just create some .php files in your web directory, and the server will parse them for you. Because it is free, most web hosts offer PHP support.



However, if your server does not support PHP, you must install PHP.



Here is a link to a good tutorial from PHP.net on how to install PHP5: http://www.php.net/manual/en/install.php



Download PHP

Download PHP for free here: http://www.php.net/downloads.php



Download MySQL Database

Download MySQL for free here: http://www.mysql.com/downloads/index.html



Download Apache Server

Download Apache for free here: http://httpd.apache.org/download.cgi

PHP Introduction

PHP is a powerful tool for making dynamic and interactive Web pages.

PHP is the widely-used, free, and efficient alternative to competitors such as Microsoft's ASP.

In our PHP tutorial you will learn about PHP, and how to execute scripts on your server.

What You Should Already Know
Before you continue you should have a basic understanding of the following:

•HTML/XHTML
•JavaScript
If you want to study these subjects first, find the tutorials on our

What is PHP?
•PHP stands for PHP: Hypertext Preprocessor
•PHP is a server-side scripting language, like ASP
•PHP scripts are executed on the server
•PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.)
•PHP is an open source software
•PHP is free to download and use

What is a PHP File?
•PHP files can contain text, HTML tags and scripts
•PHP files are returned to the browser as plain HTML
•PHP files have a file extension of ".php", ".php3", or ".phtml"

What is MySQL?
•MySQL is a database server
•MySQL is ideal for both small and large applications
•MySQL supports standard SQL
•MySQL compiles on a number of platforms
•MySQL is free to download and use

PHP + MySQL
•PHP combined with MySQL are cross-platform (you can develop in Windows and serve on a Unix platform)

Why PHP?
•PHP runs on different platforms (Windows, Linux, Unix, etc.)
•PHP is compatible with almost all servers used today (Apache, IIS, etc.)
•PHP is FREE to download from the official PHP resource: www.php.net
•PHP is easy to learn and runs efficiently on the server side

Where to Start?
To get access to a web server with PHP support, you can:

•Install Apache (or IIS) on your own server, install PHP, and MySQL
•Or find a web hosting plan with PHP and MySQL support