String replace nth occurrence - case-insensitive using PHP

str_ireplace_n.php

<?php
/**
 * String replace nth occurrence - case-insensitive
 * 
 * @param type $search  	Search string
 * @param type $replace 	Replace string
 * @param type $subject 	Source string
 * @param type $occurrence 	Nth occurrence
 * @return type 		Replaced string
 */
function str_ireplace_n($search, $replace, $subject, $occurrence)
{
	$search = preg_quote($search);
    return preg_replace("/^((?:(?:.*?$search){".--$occurrence."}.*?))$search/i", "$1$replace", $subject);
}