32位机上：
sizeof unsigned char == 1
sizeof unsigned short == 2
sizeof unsigned int == 4
sizeof unsigned long == 4
sizeof unsigned long long == 8
64位机上：
sizeof unsigned char == 1
sizeof unsigned short == 2
sizeof unsigned int == 4
sizeof unsigned long == 8
sizeof unsigned long long == 8
只有unsigned long在32、64位机上结果不同。