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PHP define() Function


PHP Misc Reference Complete PHP Misc Reference

Definition and Usage

The define() function defines a constant.

Constants are much like variables, except for the following differences:

  • A constant's value cannot be changed after it is set
  • Constant names do not need a leading dollar sign ($)
  • Constants can be accessed regardless of scope
  • Constant values can only be strings and numbers

Syntax

define(name,value,case_insensitive)
 
Parameter Description
name Required. Specifies the name of the constant
value Required. Specifies the value of the constant
case_insensitive Optional. Specifies whether the constant name should be case-insensitive. If set to TRUE, the constant will be case-insensitive. Default is FALSE (case-sensitive)


Example 1

Define a case-sensitive constant:

<?php
define("GREETING","Hello you! How are you today?");
echo constant("GREETING");
?>

The output of the code above will be:

Hello you! How are you today?


Example 2

Define a case-insensitive constant:

<?php
define("GREETING","Hello you! How are you today?",TRUE);
echo constant("greeting");
?>

The output of the code above will be:

Hello you! How are you today?


PHP Misc Reference Complete PHP Misc Reference


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