Variable Sized Struct C++

Question

Is this the best way to make a variable sized struct in C++? I don\'t want to use vector because the length doesn\'t change after initialization.

struct Pack         


        

Answer 1

You probably want something lighter than a vector for high performances. You also want to be very specific about the size of your packet to be cross-platform. But you don't want to bother about memory leaks either.

Fortunately the boost library did most of the hard part:

struct packet
{
   boost::uint32_t _size;
   boost::scoped_array _data;

   packet() : _size(0) {}

       explicit packet(packet boost::uint32_t s) : _size(s), _data(new unsigned char [s]) {}

   explicit packet(const void * const d, boost::uint32_t s) : _size(s), _data(new unsigned char [s])
   {
        std::memcpy(_data, static_cast(d), _size);
   }
};

typedef boost::shared_ptr packet_ptr;

packet_ptr build_packet(const void const * data, boost::uint32_t s)
{

    return packet_ptr(new packet(data, s));
}