får fejl i c++

hvad betyder disse nu:

  [Linker error] undefined reference to `WSAGetLastError@0'  [Linker error] undefined reference to `bind@12' 
[Linker error] undefined reference to `closesocket@4'

  [Linker error] undefined reference to `gethostbyname@4'


i denne kode






#include <time.h>
#include <errno.h>
#include <windows.h>
#include <string>
#include <iostream>
#include <stdlib.h>

#define TIMEOUT 5 // Max waiting time in sec

std::string SendReceive(char *hostname, int port, const std::string &cmd)
{
  int sd, status, len, ix, tmp;
  struct sockaddr local,remote;
  struct hostent *hostinfo;
  fd_set ReadSet;
  struct timeval Time;

  // create
  sd = socket(AF_INET, SOCK_STREAM, 0);
  if(sd == SOCKET_ERROR)
  {
    std::cerr << "Error creating socket: " << WSAGetLastError() << std::endl;
    return "";
  }

  // bind
  local.sa_family = AF_INET;
  memset(local.sa_data, 0, sizeof(local.sa_data));
  status = bind(sd, &local, sizeof(local));
  if(status == SOCKET_ERROR)
  {
    std::cerr << "Error binding socket: " << WSAGetLastError() << std::endl;
    closesocket(sd);
    return "";
  }
  // lookup host
  hostinfo = gethostbyname(hostname);
  if(!hostinfo)
  {
    std::cerr << "Error looking up host: " << hostname << ", " << WSAGetLastError() << std::endl;
    closesocket(sd);
    return "";
  }

  // connect to host
  remote.sa_family = hostinfo->h_addrtype;
  memcpy(remote.sa_data + 2, hostinfo->h_addr_list[0], hostinfo->h_length);
  *((short *)remote.sa_data) = port;

  tmp = remote.sa_data[0];
  remote.sa_data[0] = remote.sa_data[1];
  remote.sa_data[1] = tmp;
  status = connect(sd, &remote, sizeof(remote));

  if(status)
  {
    std::cerr << "Error connecting to host: " << WSAGetLastError() << std::endl;
    closesocket(sd);
    return "";
  }
  // send request
  status = send(sd, cmd.c_str(), cmd.size(), 0);
  if(status == SOCKET_ERROR)
  {
    std::cerr << "Error sending request: " << WSAGetLastError() << std::endl;
    closesocket(sd);
    return "";
  }

  // read response */
  char resp[128]; // Read at most 128 bytes
  ix = 0;
  memset(&ReadSet, 0, sizeof(ReadSet));
  FD_SET(sd, &ReadSet);
  Time.tv_sec = TIMEOUT;
  Time.tv_usec = 0;
  len = 1;

  while(len > 0 && select(sd + 1, &ReadSet, 0, 0, &Time) > 0)
  {
    len = recv(sd, resp + ix, sizeof(resp) - ix - 1, 0);
    ix += len;
    Time.tv_sec = TIMEOUT;
    Time.tv_usec = 0;
  }
  resp[ix] = 0;
  closesocket(sd);

  return resp;
}

int main()
{
  WSADATA wsaData;
  WSAStartup(MAKEWORD(1, 1), &wsaData);

  std::string Responce = SendReceive("messenger.hotmail.com", 1863, "VER 1 MSNP10 CVR0\r\n");
  std::cout << "Received: " << Responce << std::endl;
}