在Windows上使用libcurl发起HTTP请求

curl下载地址https://curl.haxx.se/download.html

当前最新版本为7.61.0

将下载的curl-7.61.0.zip解压，得到curl-7.61.0

在目录curl-7.61.0\winbuild中打开cmd

找到vcvars32.bat的位置（它在VS的安装目录中），在刚刚打开的cmd中运行此bat（目的是设置临时的环境变量，使当前的cmd可以运行nmake）

在cmd中运行nmake /f Makefile.vc mode=dll VC=<VC版本>，例如nmake /f Makefile.vc mode=dll VC=15

构建结束后，curl-7.61.0\builds\libcurl-vc15-x86-release-dll-ipv6-sspi-winssl中的lib\libcurl.lib、bin\libcurl.dll和include\curl\*.h便是我们所需要的库和头文件

GET示例

#include <stdio.h>
#include <curl/curl.h>
#pragma comment(lib, "libcurl.lib")
size_t writeFunction(void *data, size_t sizeOfEachObject, size_t numberOfObjects);
int main()
{
    curl_global_init(CURL_GLOBAL_ALL);
    CURL *curl = curl_easy_init();
    if (curl)
    {
        const char *url = "https://api.eyekey.com/face/Check/checking?app_id=f89ae61fd63d4a63842277e9144a6bd2&app_key=af1cd33549c54b27ae24aeb041865da2&url=http%3A%2F%2Fpicview01.baomihua.com%2Fphotos%2F20120713%2Fm_14_634778197959062500_40614445.jpg";
        curl_easy_setopt(curl, CURLOPT_URL, url);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeFunction);
        CURLcode curlCode = curl_easy_perform(curl);
        if (CURLE_OK != curlCode)
            fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(curlCode));
        curl_easy_cleanup(curl);
    }
    else
        printf("Something went wrong\n");
    curl_global_cleanup();
    system("pause");
    return 0;
}
size_t writeFunction(void *data, size_t sizeOfEachObject, size_t numberOfObjects)
{
    char *dataPtr = (char *)data;
    dataPtr[numberOfObjects] = '\0';
    printf("%s", dataPtr);
    return sizeOfEachObject * numberOfObjects;
}

POST示例

#include <stdio.h>
#include <curl/curl.h>
#pragma comment(lib, "libcurl.lib")
int main()
{
    curl_global_init(CURL_GLOBAL_ALL);
    CURL *curl = curl_easy_init();
    if (curl)
    {
        const char *url = "https://api.eyekey.com/face/Check/checking";
        curl_easy_setopt(curl, CURLOPT_URL, url);
        curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "app_id=f89ae61fd63d4a63842277e9144a6bd2&app_key=af1cd33549c54b27ae24aeb041865da2&url=https://gss1.bdstatic.com/9vo3dSag_xI4khGkpoWK1HF6hhy/baike/w%3D268%3Bg%3D0/sign=18bb0cc2dd1373f0f53f68999c342cc6/caef76094b36acafe725024570d98d1000e99c46.jpg");
        CURLcode curlCode = curl_easy_perform(curl);
        if (CURLE_OK != curlCode)
            fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(curlCode));
        curl_easy_cleanup(curl);
    }
    curl_global_cleanup();
    system("pause");
    return 0;
}

参考链接

Example libcurl GET request

libcurl example - http-post.c