special character

Hi, My ISP is located at USA but we are creating a system in Brazil, and the portuguese language uses several special characters. When I use these as part of a string I have trouble in the use of functions like [strtoupper] or [strtolower]. I was studying and I found a configuration function -> [setlocale], but it is necessary to put locale [setlocale(LC_ALL,locale)]. The problem is that I dont know the value for portuguese...I tried "Portuguese_Brazil" but it didin't work.... Someone could help me.... Thanks