PHP Variables

Variable is an identifier used to store value. It can be changed or removed at any time. The variable name should start with a $ sign. The syntax is,

$variable_name = value;

While declaring a variable we need not specify its data type. In PHP, the data type of its value is taken as the variable type. For example,

$message = "Welcome to PHPPOT";
$count = 5;

In this example code snippet, the $message is string variable whereas $count is int, based on the value.


PHP variable naming conventions

We need to follow the following rules while declaring variables in the PHP script.

  • The variable name should be in alphanumerics.
  • Special characters are not allowed except underscore(_).
  • It should not be pre-defined variable. For example, $this.

Types of variables

In PHP there is various type of variables. This categorization is based on the scope of the variable.

  • Global variables – These variables have global scope and visibility to access from anywhere. For accessing them in separate file, class or function we have to use global keyword. For example global $global_variable_name.
  • Local variables – The variables that are defined and used within some specific function or any other program block are called as a local variable.
  • Superglobals – These are predefined global variables. For example, $_GET, $_SERVER and etc. It can be accessed from anywhere without the global keyword.

This PHP code tutorial was published on May 17, 2013.

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