gistfile1.cpp

// ripped from http://stackoverflow.com/questions/4749325/parsing-binary-message-stream-in-c-c/4749570#4749570
// a deleted SO answer by http://stackoverflow.com/users/166749/larsmans

class unpack
{
    uint8_t *bufo, *bufp;

  public:
    unpack(uint8_t *buf) : bufo(buf), bufp(buf) { }

    unpack &operator>>(uint8_t &x)
    {
        x = *bufp++;
        return *this;
    }

    unpack &operator>>(uint16_t &x)
    {
        x  = *bufp++ << 8;
        x |= *bufp++;
        return *this;
    }

    unpack &operator>>(uint32_t &x)
    {
        x  = *bufp++ << 24;
        x |= *bufp++ << 16;
        x |= *bufp++ <<  8;
        x |= *bufp++;
        return *this;
    }

    // etc. for uint64_t; roll your own for floats
};

// Usage: read data from the wire into uint8_t buffer[SIZE_OF_MESSAGE], then

struct MsgData msg;
unpack(buffer) >> msg.num >> msg.x >> ... >> msg.elevation;