PHP constants

A constant is an identifier (name) for a simple value. As the name suggests, that value cannot change during the execution of the script Constants are case-sensitive. By convention, constant identifiers are always uppercase.

• Constants variable are automatically global and can be used across the entire script.
• A valid constant variable name starts with a letter or underscore

Syntax

define(identifier,value,case-insensitive);

To create a constant variable , use the define() function.

Example

// Valid constant names
define("FOO",     "something");
define("FOO2",    "something else");
define("FOO_BAR", "something more");

// Invalid constant names
define("2FOO",    "something");

Parameters