What's worse, tolower() and toupper() are locale-dependent. In most locales, tolower("I") = "i" but in Turkish, tolower("I") = "ı" Same in the other dir

What's worse, tolower() and toupper() are locale-dependent. In most locales, tolower("I") = "i" but in Turkish, tolower("I") = "ı" Same in the other direction, because there is also a large I with dot.