check_encoding

$string = 'привет, мир!';

function check_encoding($string) {
  $encodings = mb_list_encodings();
  foreach ($encodings as $encoding) {
    $str[$encoding] = iconv("UTF-8", $encoding, $string);
  }
 return $str;
}

echo '<pre>';
print_r(check_encoding($string));
echo '</pre>';