PHP Constant

A constant in PHP is a fixed value that cannot be changed after it is created.

• Value cannot change
• A valid constant name starts with a letter or underscore  $ sign can not use before constant define.
• Available globally
• Mostly written in CAPITAL letters
• Constants are case-sensitive by default.

How to Create Constants in PHP

1. Using define():

define(name, value, case-insensitive);

• name: The name of the constant.
• value: The value of the constant.
• case-insensitive (optional): Indicates whether the constant name should be case-insensitive. Default is false.

<?php
define("SITE_NAME", "TutorialsonWeb");
echo SITE_NAME;
?>

2. Using const:

<?php
const PI = 3.14;
echo PI;
?>