Sending Vector Winsock Problems - c++

Question

first time asking a question!
I have a small server that sends a vector of objects to a client:
void sendFoo(vector<Foo> &foo){
int num = foo.size();
sSend = accept(sListen, (SOCKADDR*)&addr, &addrLen);
for(int i = 0; i < num; i++){
if(sSend == NULL){
cout << "Not connected" << endl;
} else {
//send vector size
send(sSend, (char*)&num, sizeof(num), NULL);
//send foo(s)
send(sSend, (char*)&foo[i], sizeof(foo[i]), NULL);
}
}
closesocket(sSend);
}
The foo class contains an int id and a double transformation[3][4].
My client app prints out the ids and the transformations it receives:
sRecv = socket(AF_INET, SOCK_STREAM, NULL);
if (connect(sRecv, (SOCKADDR*)&addr, addrLen) != 0) {
cout << "Not connected to server" << endl;
} else {
recv(sRecv, (char*)&num, sizeof(num), NULL);
vector<Foo> foo(num);
for (int i = 0; i < num; i++){
recv(sRecv, (char*)&foo[i], sizeof(foo[i]), NULL);
//prints them out
}
}
If I create 1 Foo and send it across the client correctly prints this:
Foo ID: 1
Foo Transformation:
1.0000 2.0000 3.0000 4.0000
1.0000 2.0000 3.0000 4.0000
1.0000 2.0000 3.0000 4.0000
But when I try to send across more than one I get what look like memory references every other block:
Foo ID: 1
Foo 1 Transformation:
1.0000 2.0000 3.0000 4.0000
1.0000 2.0000 3.0000 4.0000
1.0000 2.0000 3.0000 4.0000
Foo ID: 4
Foo 4 Transformation:
-6.27744e+66 -6.27744e+66 -6.27744e+66 -6.27744e+66
-6.27744e+66 -6.27744e+66 -6.27744e+66 -6.27744e+66
-6.27744e+66 -6.27744e+66 -6.27744e+66 -6.27744e+66
Foo ID: 2
Foo 2 Transformation:
1.0000 2.0000 3.0000 4.0000
1.0000 2.0000 3.0000 4.0000
1.0000 2.0000 3.0000 4.0000
Foo ID: 4
Foo 4 Transformation:
1.70592e-314 5.29981e-315 5.30499e-315 5.30758e-315
5.31017e-315 5.29981e-315 5.30499e-315 5.30758e-315
5.31017e-315 5.29981e-315 5.30499e-315 5.30758e-315
//etc
[SOLVED] I was trying to send the size of the vector multiple times and the client was only set up to receive it once. Thanks for the answers!

Answer 1

Well, I'd say a debugger will be your best friend. I'm also a little surprised the received end gave the printed output you show, perhaps more issues that aren't shown.
Look at the location of the following line:
send(sSend, (char*)&num, sizeof(num), NULL);
And compare to where you have the receiving of that:
recv(sRecv, (char*)&num, sizeof(num), NULL);
Hint, you call send more than recv.

Answer 2

To send your class over a socket you need to serialize it in a raw chunk of memory. you can't send the C++ object directly.
Make a function uint_32_t Foo::exportRaw( void **buffer) ; that will allocate raw memory for a buffer, put you class' members in it, then return the size allocated to send it over the socket.
Don't forget to free your buffer memory when it is sent and useless.
Here is an example :
void *buffer;
uint32_t sizeAlloc;
sizeAlloc = foo[i].exportRaw(&buffer); // serialize object
//send foo(s)
send(sSend, (char*)buffer, sizeAlloc, NULL);
free(buffer);