Unsigned char cout hex Using std::ostringstream. Like unsigned char, it can be used to access raw memory occupied Instead of writing your own implementation for int_to_bin, consider exploiting std::bitset. I suppose a full test would be what you've done before, which is to take an array from 0x00 through 0xFF and convert that from pure binary to a HEX string using your toHex() The output of an unsigned char is like the output of a char which obviously does not what the OP expects. Convert unsigned char the way printf does in C++. No matter how big a char is, once you're representing it as an ASCII sequence I've looked through all previous version of this topic and none have seemed to help. flags(ios::hex); cout << hexVal << endl; Yes. Non-zero value if the character is a hexadecimal numeric character, zero otherwise. Preferrably with some hex dump utility. The SHA1 code I used holds the sum in a byte array which is basically an array of unsigned chars. print(char, HEX) a char with a negative value -1 ~ -128 displays a long value rather than the byte value. sgscvbaisqwxncloisvinfohxchvbsdrfigrylmlsssjlwtheaykcilwertceagbxjkzwef