socket program noob spm

jeg er lige ved at lave lidt winsock programmering men kan ikke helt finde ud af hvad der er galt:


#include "stdafx.h"
#include <winsock.h>
#include <iostream.h>
#include <string.h>

int main(int argc, char* argv[])
{
    call_socket("192.168.1.2","3940");
    return 0;
}

SOCKET call_socket(const char *hostname, unsigned short portnum)
    {
    struct sockaddr_in sa;
    struct hostent *hp;
    SOCKET s; hp = gethostbyname(hostname);
    if (hp == NULL) /* we don't know who this host is */
        return INVALID_SOCKET;
    memset(&sa,0,sizeof(sa));
    memcpy((char *)&sa.sin_addr, hp->h_addr, hp->h_length); /* set address */
    sa.sin_family = hp->h_addrtype;
    sa.sin_port = htons((u_short)portnum);
    s = socket(hp->h_addrtype, SOCK_STREAM, 0);
    if (s == INVALID_SOCKET)
    return INVALID_SOCKET; /* try to connect to the specified socket */
    if (connect(s, (struct sockaddr *)&sa, sizeof sa) == SOCKET_ERROR) {
        closesocket(s);
        return INVALID_SOCKET; }
    return s;

error:

error C2065: 'call_socket' : undeclared identifier
error C2373: 'call_socket' : redefinition; different type modifiers