std::ifstream crcfile(filename, std::ios::binary);
std::ifstream crcfile(filename, std::ios::binary | std::ios::in);
uint32 crc32(const char *filename){	std::ifstream crcfile(filename, std::ios::binary);	uint32 crc32val = 0;	unsigned char c;	crcfile.get(reinterpret_cast<char &>(c));	while (crcfile.good()) {		crc32val = crc32_tab[(crc32val ^ c) & 0xff] ^ (crc32val >> 8);		crcfile.get(reinterpret_cast<char &>(c));	}	return crc32val;}