W3Schools.com

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
WEB HOSTING
Best Web Hosting
PHP MySQL Hosting
Best Hosting Coupons
UK Reseller Hosting
Cloud Hosting
Top Web Hosting
$7.95/mo SEO Hosting
Premium Website Design
WEB BUILDING
Download XML Editor
FREE Website BUILDER
Free Website Templates Free CSS Templates
Make Your Own Website
W3SCHOOLS EXAMS
Get Certified in:
HTML, CSS, JavaScript, XML, PHP, and ASP
W3SCHOOLS BOOKS
New Books:
HTML, CSS
JavaScript, and Ajax
STATISTICS
Browser Statistics
Browser OS
Browser Display
SHARE THIS PAGE