HexHelper.h

#ifndef HEXHELPER_H
#define HEXHELPER_H

class HexHelper
{
private:
    static const char* hex_char_to_bin(char c)
    {
        // TODO handle default / error
        switch(toupper(c))
        {
            case '0': return "0000";
            case '1': return "0001";
            case '2': return "0010";
            case '3': return "0011";
            case '4': return "0100";
            case '5': return "0101";
            case '6': return "0110";
            case '7': return "0111";
            case '8': return "1000";
            case '9': return "1001";
            case 'A': return "1010";
            case 'B': return "1011";
            case 'C': return "1100";
            case 'D': return "1101";
            case 'E': return "1110";
            case 'F': return "1111";
            default: return "0000";
        }
    }

public:
    static std::string hex_str_to_bin_str(const std::string& hex)
    {
        // TODO use a loop from <algorithm> or smth
        std::string bin;
        for(unsigned i = 0; i != hex.length(); ++i)
           bin += hex_char_to_bin(hex[i]);
        return bin;
    }
};

#endif // HEXHELPER_H