After reading the PNG specification I was a little bit surprised. I've read character literals should be hardcoded with binary values like 0x41 not in (the programmer friendly) 'A'. The problem seems to be that character literals are differently encoded during compilation on different systems with different underlying character sets.
Okay well I asked friends and read the C++ Standard (ISO/IEC 14882:1998/e) but I didn't get/found the answer if the conversation depends on the system that I use to compile or it's a fixed character set (like ASCII) ever?
Thanks for your answers.