- error_reporting: documentation ( source)
- define: documentation ( source)
<?php
error_reporting(E_ALL);
define('great','my');
$great='fantastic';
$my='my value';
echo ${great }, "<br/>\n";//output:my value
echo ${ great}, "<br/>\n";//output:my value
echo ${ great }, "<br/>\n";//output:my value
echo ${great}, "<br/>\n";//output:my value