c++ - winhttp 和 Visual Studio 代码 - 构建时完成 newb 和“未定义引用”问题

Question

我有大约 20 年的 php、js、css、html、xml 等（所有网络内容），但在 C++ 中什么都没有——这里是完整的新手。我快速学习代码，但最好使用我可以“玩”以更好地理解的工作示例。

我安装了 VS Code，安装了 c/c++ 扩展和 MinGW-x64 编译器（我一直在关注https://code.visualstudio.com/docs/languages/cpp。我还安装了最新的 Windows SDK。

我正在尝试使用下面的示例，我相信我在这里找到了 SO，它对 php 脚本进行了简单的测试“POST”。我敢肯定这对大多数人来说都是可笑的，而且事情是错误的，但现在这对我来说都是陌生的，除了纯粹通过了解其他语言来基本了解正在发生的事情。任何帮助，将不胜感激。

#include <Windows.h>
#include <WinHttp.h>
#include <stdio.h>
#include <iostream> //getchar
#include <fstream>

#pragma comment(lib, "winhttp.lib")

using namespace std;

std::wstring get_utf16(const std::string &str, int codepage)
{
    if (str.empty()) return std::wstring();
    int sz = MultiByteToWideChar(codepage, 0, &str[0], (int)str.size(), 0, 0);
    std::wstring res(sz, 0);
    MultiByteToWideChar(codepage, 0, &str[0], (int)str.size(), &res[0], sz);
    return res;
}

string HttpsWebRequestPost(string domain, string url, string dat)
{
    //Extra
    LPSTR  data = const_cast<char *>(dat.c_str());;
    DWORD data_len = strlen(data);

    wstring sdomain = get_utf16(domain, CP_UTF8);
    wstring surl = get_utf16(url, CP_UTF8);
    string response;

    DWORD dwSize = 0;
    DWORD dwDownloaded = 0;
    LPSTR pszOutBuffer;
    BOOL  bResults = FALSE;
    HINTERNET  hSession = NULL,
        hConnect = NULL,
        hRequest = NULL;
    LPCWSTR additionalHeaders = L"Content-Type: application/x-www-form-urlencoded\r\n";
    DWORD headersLength = -1;

    // Use WinHttpOpen to obtain a session handle.
    hSession = WinHttpOpen(L"WinHTTP Example/1.0",
        WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
        WINHTTP_NO_PROXY_NAME,
        WINHTTP_NO_PROXY_BYPASS, 0);

    // Specify an HTTP server.
    if (hSession)
        hConnect = WinHttpConnect(hSession, sdomain.c_str(),
            INTERNET_DEFAULT_HTTP_PORT, 0);

    // Create an HTTP request handle.
    if (hConnect)
        hRequest = WinHttpOpenRequest(hConnect, L"POST", surl.c_str(),
            NULL, WINHTTP_NO_REFERER,
            WINHTTP_DEFAULT_ACCEPT_TYPES,
            0);

    // Send a request.
    if (hRequest)

        bResults = WinHttpSendRequest(hRequest,
                                        additionalHeaders,
                                        headersLength,
                                        (LPVOID)data,
                                        data_len,
                                        data_len, 
                                        0);

    // End the request.
    if (bResults)
        bResults = WinHttpReceiveResponse(hRequest, NULL);

    // Keep checking for data until there is nothing left.
    if (bResults)
    {
        do
        {
            // Check for available data.
            dwSize = 0;
            if (!WinHttpQueryDataAvailable(hRequest, &dwSize))
                printf("Error %u in WinHttpQueryDataAvailable.\n",
                    GetLastError());

            // Allocate space for the buffer.
            pszOutBuffer = new char[dwSize + 1];
            if (!pszOutBuffer)
            {
                printf("Out of memory\n");
                dwSize = 0;
            }
            else
            {
                // Read the data.
                ZeroMemory(pszOutBuffer, dwSize + 1);

                if (!WinHttpReadData(hRequest, (LPVOID)pszOutBuffer,
                    dwSize, &dwDownloaded))
                    printf("Error %u in WinHttpReadData.\n", GetLastError());
                else
                    //printf("%s", pszOutBuffer);
                    response = response + string(pszOutBuffer);
                // Free the memory allocated to the buffer.
                delete[] pszOutBuffer;
            }
        } while (dwSize > 0);
    }

    // Report any errors.
    if (!bResults)
        printf("Error %d has occurred.\n", GetLastError());

    // Close any open handles.
    if (hRequest) WinHttpCloseHandle(hRequest);
    if (hConnect) WinHttpCloseHandle(hConnect);
    if (hSession) WinHttpCloseHandle(hSession);

    return response;
}

int main()
{ 
    printf("RESPONSE: %S\n", HttpsWebRequestPost("example.com", "/example.php", "value=1000").c_str());
    system("PAUSE");
}

构建后，我在控制台中得到以下信息：

Starting build...
Build finished with errors(s):
C:\Users\*****\AppData\Local\Temp\cczChaiv.o: In function `HttpsWebRequestPost(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)':
C:/*****/test.cpp:42: undefined reference to `WinHttpOpen'
C:/*****/test.cpp:49: undefined reference to `WinHttpConnect'
C:/*****/test.cpp:54: undefined reference to `WinHttpOpenRequest'
C:/*****/test.cpp:62: undefined reference to `WinHttpSendRequest'
C:/*****/test.cpp:72: undefined reference to `WinHttpReceiveResponse'
C:/*****/test.cpp:81: undefined reference to `WinHttpQueryDataAvailable'
C:/*****/test.cpp:97: undefined reference to `WinHttpReadData'
C:/*****/test.cpp:114: undefined reference to `WinHttpCloseHandle'
C:/*****/test.cpp:115: undefined reference to `WinHttpCloseHandle'
C:/*****/test.cpp:116: undefined reference to `WinHttpCloseHandle'
collect2.exe: error: ld returned 1 exit status

The terminal process terminated with exit code: -1.

标签： c++visual-studio-codewinhttp