<?php
define("hello", "Hi There.");
echo hello; // outputs "Hi There."
echo "\n";
echo Hello; // outputs "Hello" and issues a notice in the browser.
echo "\n";
//To allow case insensitive, set the third parameter to be true.
define("greeting", "How are you?", true);
echo GREETING; // outputs "How are you?"
echo "\n";
echo Greeting; // outputs "How are you?."
?>