function func_substr_replace($str, $replacement = '*', $start = 1, $length = 3)
{
$len = mb_strlen($str,'utf-8');
if ($len > intval($start+$length)) {
$str1 = msubstr($str,0,$start);
$str2 = msubstr($str,intval($start+$length),NULL);
} else {
$str1 = msubstr($str,0,1);
$str2 = msubstr($str,$len-1,1);
$length = $len - 2;
}
$new_str = $str1;
for ($i = 0; $i < $length; $i++) {
$new_str .= $replacement;
}
$new_str .= $str2;
return $new_str;
}