convert a char to its hex representation

char_to_hex.h

std::string char_to_hex(unsigned char input)
{
    static const char* const dict = "0123456789ABCDEF";
    std::string result("0x");
    result.push_back(dict[input >> 4]);
    result.push_back(dict[input & 0x0F]);
    return result;
}