ucfirst function with utf-8 turkish chars

ucfirstTurkish.php

<?
function iConverterTurkish($str, $dir="upper"){
	$low = array('ı','i','ğ','ü','ş','ö','ç');
	$up  = array('I','İ','Ğ','Ü','Ş','Ö','Ç');
    	return $dir=="upper" ? 
     		str_replace($low, $up, $str) : 
     		str_replace($up, $low, $str) ;
}

function ucfirstTurkish($str) {
	$tmp = preg_split("//u", $str, 2, PREG_SPLIT_NO_EMPTY);
	return 
		strtoupper(iConverterTurkish($tmp[0],"upper")).
		strtolower(iConverterTurkish($tmp[1],"lower"));
}

echo ucfirstTurkish("iyİlikLIdırÖ"); // return İyiliklıdırö
?>