C++ hex string to byte array

Question

I'm trying to send a string of hex values through udp,

11 22 33 44 37 4D 58 33 38 4C 30 39 47 35 35 34 31 35 31 04 D7 52 FF 0F 03 43 2D AA

using UdpClient in C++.

What's the best way to convert string^ to  array< Byte >^ ?

Answer 1

This works for me, although I haven't tested the error-detection all that well.

ref class Blob
{
    static short* lut;
    static Blob()
    {
        lut = new short['f']();
        for( char c = 0; c < 10; c++ ) lut['0'+c] = 1+c;
        for( char c = 0; c < 6; c++ ) lut['a'+c] = lut['A'+c] = 11+c;
    }
public:
    static bool TryParse(System::String^ s, array<System::Byte>^% arr)
    {
        array<System::Byte>^ results = gcnew array<System::Byte>(s->Length/2);
        int index = 0;
        int accum = 0;
        bool accumReady = false;
        for each (System::Char c in s) {
            if (c == ' ') {
                if (accumReady) {
                    if (accum & ~0xFF) return false;
                    results[index++] = accum;
                    accum = 0;
                }
                accumReady = false;
                continue;
            }
            accum <<= 4;
            accum |= (c <= 'f')? lut[c]-1: -1;
            accumReady = true;
        }
        if (accumReady) {
            if (accum & ~0x00FF) return false;
            results[index++] = accum;
        }
        arr = gcnew array<System::Byte>(index);
        System::Array::Copy(results, arr, index);
        return true;
    }
};

Answer 2

If you're trying to send that as ascii bytes, then you probably want System::Text::Encoding::ASCII::GetBytes(String^).

If you want to convert the string to a bunch of bytes first (so first byte sent is 0x11), you'll want to split your string based on whitespace, call Convert::ToByte(String^, 16) on each, and put them into an array to send.