Question

Simple question here. Having a problem with the XOR operator (^). I can XOR integers fine and get the correct results; however, when XORing two chars, nothing is returned:

int main() {
    char a = 'a';
    char b = 'b';
    char c;

    c = a^b;
    cout << c << endl;
}

Nothing happens. No output. What am I doing wrong here. I’m trying to use this to XOR encrypt a string with a given key, but am having issues with this operation. I guess I could get the ASCII value and convert it to its corresponding char, but this tool will be used to encrypt files as well as plain text so I would like to avoid that at all costs.

Answer 1

std::ostream::operator<< (and std::cout is an std::ostream) outputs formatted text. When you pass it a char, it’s trying to format and output a character (think ASCII). If the char isn’t a printable character, it doesn’t print it out (for obvious reasons). If you want it to output a formated integer, you need to cast it:

char a = 'a'; // 'a' == 0x61
char b = 'b'; // 'b' == 0x62
char c = a ^ b; // 0x61 ^ 0x62 == 0x03
std::cout << static_cast<int>(c) << std::endl;

For what it’s worth, if you use the unformatted output function std::ostream::write, it will output unformatted characters. Beware, however, because if you try to write out an unprintable character, it will “work,” but your console will not show it (because again, it’s an unprintable character).