Constant in PHP

Constant in PHP

Constants are name or identifier that can't be changed during the execution of the script. In php constants are define in two ways;

• Using define() function
• Using const keyword

In php decalare constants follow same rule variable declaration. Constant start with letter or underscore only.

Create a PHP Constant

Create constant in php by using define() function.

define((name, value, case-insensitive)

• name: Specifies the name of the constant
• value: Specifies the value of the constant
• case-insensitive: Specifies whether the constant name should be case-insensitive. Default is false

In below example we create constant with case-sensitive

<?php
define("MSG","Hello world!");  
echo MSG;  
?>

In below example we create constant with case-insensitive

<?php
define("MSG","Hello world!", true);  
echo msg;  
?>

Define constant using cons keyword in php

The const keyword defines constants at compile time. It is a language construct not a function. It is bit faster than define(). It is always case sensitive.

<?php
cons MSG="Hello world!";  
echo MSG;
?>