Peter Eisentraut <peter.eisentraut@xxxxxxxxxxxxxxxx> writes: > Running lower() like this is really the wrong thing to do. We should be > doing "case folding" instead, which normalizes these differences for the > purpose of case-insensitive comparisons. That just begs the question: if tolower (or towlower) isn't the appropriate API, what is? Perhaps ICU has something for a more generalized notion of case-similarity, but I'm not aware of any such thing in the POSIX API. BTW, I think it's only accidental that the regex example shown upthread gets the right answer. In that example, what's happening is that we consider a letter in a case-insensitive regex to match itself, or tolower() of itself, or toupper() of itself. Both σ and ς have Σ as toupper() so they both work. But if you'd written Σ in the regex, only one of σ and ς would match that as a data character. (Haven't actually tested this, but given the way the code works I'm pretty sure it's so.) Again, it's hard to see how to do better atop a POSIX locale library. regards, tom lane
