utf 8 - strtoupper PHP function for UTF-8 string

Question

I've been reading user comments for the strtoupper() PHP function and there doesn't seem to a consensus on how to do the conversion for non-Enlgish strings. I mean people offer localized solutions and stuff, but shouldn't there be a uniform way to convert a string to all upper (or all lower) case letters?

So my question is, say, if I have a UTF-8 encoded string (in some unknown locale) how do I convert it to all upper/lower letters in PHP?

Answer 1

You want to use mb_strtoupper.

$str = "Τ?χιστη αλ?πηξ βαφ?? ψημ?νη γη, δρασκελ?ζει υπ?ρ νωθρο? κυν??";
$str = mb_strtoupper($str, "UTF-8");
echo $str; // Prints Τ?ΧΙΣΤΗ ΑΛ?ΠΗΞ ΒΑΦ?Σ ΨΗΜ?ΝΗ ΓΗ, ΔΡΑΣΚΕΛ?ΖΕΙ ΥΠ?Ρ ΝΩΘΡΟ? ΚΥΝ?Σ

PHP.net states:

By contrast to the standard case folding functions such as strtolower() and strtoupper(), case folding is performed on the basis of the Unicode character properties. Thus the behaviour of this function is not affected by locale settings and it can convert any characters that have 'alphabetic' property, such as A-umlaut (?).