CODE EXAMPLE FOR PHP

strtoupper php

setlocale(LC_CTYPE, 'de_DE.UTF8');

// be noted
echo strtoupper('Umlaute äöü in uppercase'); // outputs "UMLAUTE äöü IN UPPERCASE"
echo mb_strtoupper('Umlaute äöü in uppercase', 'UTF-8'); // outputs "UMLAUTE ÄÖÜ IN UPPERCASE"