c++ - 'getaddrinfo' : identifier not found

Question

我开始在 Visual Studio 2017 中使用 C++ 在 Windows 7 上进行 WinSock 2 编程。我正在尝试在此处启动并运行 winsock 客户端示例代码:https://msdn.microsoft.com/en-us/library/windows/desktop/ms737591(v=vs.85).aspx

我不得不删除 windows.h 包含以删除一大堆错误，但有 2 个我无法删除(彼此相关)。当我尝试构建时，收到以下错误消息: C3861 freeaddrinfo':找不到标识符 C3861 getaddrinfo':找不到标识符

令人沮丧的是，visual studio 似乎能够解析这些引用。从代码中，我可以右键单击->转到定义，这两个错误都没有任何问题。我正在链接到 ws2_32.lib，所以这也不是问题。我在 Windows XP 或更早版本的搜索中遇到过此问题的其他实例，例如这个 GetAddrInfo identifier not found .但我在 Windows 7 上，所以操作系统兼容性不应该是问题。我还尝试包含 ws2tcpip.h 和 wspiapi.h，但这没有帮助。

为了完整起见，这里是我所有的代码:

#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;
}

还有我的 stdafx.h 文件:

// 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

任何想法将不胜感激。

Answer 1

您的 header 顺序错误。 #include "stdafx.h" 应该始终是 .c 或 .cpp 文件的第一个头文件。 (当使用预编译的 headdrs 时)。

这是 stdafx.h 所需要的:

#pragma once

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

这是你的主源文件顶部所需要的:

#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)
{
...