#1 Use mb_check_encoding for utf8_is_valid

[aprisobal]

What do you think about using function mb_check_encoding to check utf8 string? i.e.:

function utf8_is_valid($str) {
if (function_exists('mb_check_encoding')) {
return mb_check_encoding($str, 'UTF-8');
}

...

[George Petsagourakis]

The mb_check_encoding is not doing a good job checking the encoding according to standards. Check http://php.net/manual/en/function.mb-check-encoding.php