PHP constants

Set PHP constants

To set constants, use the define() function - it takes three parameters:

The first parameter defines the name of the constant

The second parameter defines the value of the constant

The optional third This parameter specifies whether the constant name is case-sensitive. The default is false.

The following example creates a case-sensitive constant with the value "Welcome to W3School.com.cn!":

Instance

<?php
define("GREETING", "Welcome to W3School.com.cn!");
echo GREETING;
?>

Running instance

The following example creates a case-insensitive constant, The value is "Welcome to W3School.com.cn!":

Instance

<?php
define("GREETING", "Welcome to W3School.com.cn!", true);
echo greeting;
?>