用于UTF-8字符串的strtoupper PHP函数

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?I've been reading user comments for the strtoup