serialization of float vector in a struct - c++

Question

I have the following code:
struct MsgDetectedTarget
{
int target_id;
float bbox[4]; // need to change
};
in a serialization function :
void SerializeToArray(std::vector<char>& buffer, int& dst_len, void* pMsg, int len){
buffer.resize(HEADER_LENGTH + len);
// encode message header
char header[HEADER_LENGTH + 1] = "";
std::sprintf(header, "%8d", len);
std::memcpy(&buffer[0], header, HEADER_LENGTH);
// encode message body
std::memcpy(&buffer[0]+HEADER_LENGTH, reinterpret_cast<char*>(pMsg), len);
dst_len = HEADER_LENGTH + len;
}
if the data bbox in MsgDetectedTarget is of fixed size, it is easy to do the serialization.
MsgDetectedTarget msg;
msg.target_id = 1;
msg.bbox[0] = 0;
msg.bbox[1] = 0;
msg.bbox[2] = 500;
msg.bbox[3] = 500;
std::vector<char> msgdata;
int destlen;
SerializeToArray(msgdata, destlen, &msg, sizeof(msg));
Problem:
I want to change the bbox in MsgDetectedTarget to be a vector of float, How can I perform corresponding serialization and deserialization?
Thanks very much.

Answer 1

If you cannot use Boost serialization, you can do what #Jean-FrancoisFabre suggested. Something like:
void SerializeToArray(std::vector<char>& buffer, int& dst_len, MsgDetectedTarget* msg) {
size_t numFloats = msg->bbox.size();
auto len = sizeof(int) + sizeof(size_t) + sizeof(float)*numFloats;
buffer.resize(HEADER_LENGTH + len);
// encode message header
char header[HEADER_LENGTH + 1] = "";
std::sprintf(header, "%8d", len);
std::memcpy(&buffer[0], header, HEADER_LENGTH);
// encode target_id
std::memcpy(&buffer[0] + HEADER_LENGTH, static_cast<char*>(&msg->target_id), sizeof(int));
// encode numFloats
std::memcpy(&buffer[0] + HEADER_LENGTH + sizeof(int), static_cast<char*>(&numFloats), sizeof(size_t));
// encode the vector of float
std::memcpy(&buffer[0] + HEADER_LENGTH + sizeof(int) + sizeof(size_t),
static_cast<char*>(&bbox[0]), sizeof(float)*numFloats);
dst_len = HEADER_LENGTH + len;
}