How to check if letter is upper or lower in PHP?

Question

I have texts in UTF-8 with diacritic characters also, and would like to check if first letter of this text is upper case or lower case. How to do this?

Answer 1

function starts_with_upper($str) {
    $chr = mb_substr ($str, 0, 1, "UTF-8");
    return mb_strtolower($chr, "UTF-8") != $chr;
}

Note that mb_substr is necessary to correctly isolate the first character.