php random string

This is a tiny function that makes a random string of predefined length.
It does not use letters and numbers that could be confusing, like O and 0.

// Make a random string
function makeRandomString($length){
        $str = array('a','b','c','d','f','g','h','j','k','m','n','p','q','r','s','t','w','x','y','z','A','B','C','D','E','F','G','H','J','K','M','N','P','Q','R','S','T','W','X','Y','Z','2','4','5','6','7','8','9');
        $nkeys = array_rand($str, $length);
        $nstr = '';
        foreach($nkeys as $key){ $nstr .= $str[$key]; }
        return $nstr;
}

// Make a random string
function makeRandomString($length){
	$str = array('a','b','c','d','f','g','h','j','k','m','n','p','q','r','s','t','w','x','y','z','A','B','C','D','E','F','G','H','J','K','M','N','P','Q','R','S','T','W','X','Y','Z','2','4','5','6','7','8','9');
	$nkeys = array_rand($str, $length);
	$nstr = '';
	foreach($nkeys as $key){ $nstr .= $str[$key]; }
	return $nstr;
}