'getaddrinfo': identifier not found

Question

I am getting started with WinSock 2 Programming on Windows 7 using C++ in Visual Studio 2017. I am trying to get the winsock client example code here up and running: https://msdn.microsoft.com/en-us/library/windows/desktop/ms737591(v=vs.85).aspx

I had to remove the windows.h inclusion in order to remove a whole bunch of errors, but there are 2 that I can't get rid of (related to each other). When I try to build, I get the following error messages: C3861 freeaddrinfo': identifier not found C3861 getaddrinfo': identifier not found

The frustrating thing is that visual studio seems to be able to resolve these references. From the code, I can right-click->go to definition without any issues for both errors. I am linking to ws2_32.lib so that isn't the problem either. I've come across other instances of this problem on Windows XP or earlier in my searching, such as this one GetAddrInfo identifier not found. But I'm on Windows 7, so OS compatibility shouldn't be the issue. I also tried including ws2tcpip.h and wspiapi.h, but that didn't help.

Here's all of my code for completeness' sake:

#include <ws2tcpip.h>
#include <wspiapi.h>
#include <stdlib.h>
#include <stdio.h>
#include "stdafx.h"

// Need to link with Ws2_32.lib, Mswsock.lib, and Advapi32.lib
#pragma comment (lib, "Ws2_32.lib")
#pragma comment (lib, "Mswsock.lib")
#pragma comment (lib, "AdvApi32.lib")

#define DEFAULT_BUFLEN 512
#define DEFAULT_PORT "27015"

int __cdecl main(int argc, char **argv)
{
    WSAData wsaData;
    SOCKET ConnectSocket = INVALID_SOCKET;
    struct addrinfo *result = NULL,
        *ptr = NULL,
        hints;
    char *sendbuf = "this is a test";
    char recvbuf[DEFAULT_BUFLEN];
    int iResult;
    int recvbuflen = DEFAULT_BUFLEN;

    // Validate the parameters
    if (argc != 2) {
        printf("usage: %s server-name\n", argv[0]);
        return 1;
    }

    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    // Resolve the server address and port
    iResult = getaddrinfo(argv[1], DEFAULT_PORT, &hints, &result);
    if (iResult != 0) {
        printf("getaddrinfo failed with error: %d\n", iResult);
        WSACleanup();
        return 1;
    }

    // Attempt to connect to an address until one succeeds
    for (ptr = result; ptr != NULL; ptr = ptr->ai_next) {

        // Create a SOCKET for connecting to server
        ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype,
            ptr->ai_protocol);
        if (ConnectSocket == INVALID_SOCKET) {
            printf("socket failed with error: %ld\n", WSAGetLastError());
            WSACleanup();
            return 1;
        }

        // Connect to server.
        iResult = connect(ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
        if (iResult == SOCKET_ERROR) {
            closesocket(ConnectSocket);
            ConnectSocket = INVALID_SOCKET;
            continue;
        }
        break;
    }

    freeaddrinfo(result);

    if (ConnectSocket == INVALID_SOCKET) {
        printf("Unable to connect to server!\n");
        WSACleanup();
        return 1;
    }

    // Send an initial buffer
    iResult = send(ConnectSocket, sendbuf, (int)strlen(sendbuf), 0);
    if (iResult == SOCKET_ERROR) {
        printf("send failed with error: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }

    printf("Bytes Sent: %ld\n", iResult);

    // shutdown the connection since no more data will be sent
    iResult = shutdown(ConnectSocket, SD_SEND);
    if (iResult == SOCKET_ERROR) {
        printf("shutdown failed with error: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }

    // Receive until the peer closes the connection
    do {

        iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
        if (iResult > 0)
            printf("Bytes received: %d\n", iResult);
        else if (iResult == 0)
            printf("Connection closed\n");
        else
            printf("recv failed with error: %d\n", WSAGetLastError());

    } while (iResult > 0);

    // cleanup
    closesocket(ConnectSocket);
    WSACleanup();

    return 0;
}

And my stdafx.h file:

// stdafx.h : include file for standard system include files,
// or project specific include files that are used frequently, but
// are changed infrequently
//

#pragma once

#include "targetver.h"

#include <stdio.h>
#include <tchar.h>

#define _WINSOCK_DEPRECATED_NO_WARNINGS
#include <WinSock2.h>
#pragma comment(lib, "WS2_32.lib")


// TODO: reference additional headers your program requires here

Any ideas would be much appreciated.

Answer 1

Your headers are in the wrong order. #include "stdafx.h" should always be the first header include for a .c or .cpp file. (when using precompiled headedrs).

This is what's needed for stdafx.h:

#pragma once

#include "targetver.h"
#include <ws2tcpip.h>   // includes <winsock2.h> implicitly which in turn includes <windows.h>
#include <stdlib.h>
#include <stdio.h>

This what's needed at the top of your main source file:

#include "stdafx.h"

// Need to link with Ws2_32.lib
#pragma comment (lib, "Ws2_32.lib")


#define DEFAULT_BUFLEN 512
#define DEFAULT_PORT "27015"

int __cdecl main(int argc, char **argv)
{
...