PHP Tutorial – Variables

In this PHP programming language tutorial we will look at variables. A variable is used to store information or values in, like text-strings, numbers or arrays. As long as you don’t remove the value in a variable then you can use the variable (thus the value) over and over again.

PHP Variable Declaration

All variables in PHP begin with the $ sign. A common mistake of new PHP programmers is to forget the $ sign before a variable, so don’t forget it!

Let’s look at a variable declaration in PHP:

<?php
     $my_variable = 20;
     $my_variable2 = “Hello World”;
?>

First we declare a variable $my_variable with the value of 20. The second variable declaration we use a string “Hello World”.

Note: in both cases we end with a semicolon. The semicolon marks the end of the statement. If you forget a semicolon you will get an unexpected result or the program will do nothing. So don’t forget to end a statements with a semicolon!

Note 2: for people that have written programs in other language, such as C/C++ for instance, you don’t have to determine the data type of the variable (example in C Language: int my_var = 20; .) The PHP language is a loosely typed language, which means that PHP automatically converts the variable to the correct data type, depending on its value. The C/C++ languages are strongly typed programming languages.

Variable Rules

You have to follow some rules when naming a variable:

• A variable name cannot contain spaces.
• 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 _ )

That’s all for this PHP tutorial on variables in PHP.