C++使用curl下载文件（get请求）

使用curl也可以下载文件，代码如下：

#include<iostream>
#include<string>
#include<curl\curl.h>
using namespace std;

//下载文件数据接收函数
size_t dl_req_reply(void *buffer, size_t size, size_t nmemb, void *user_p)
{
    FILE *fp = (FILE *)user_p;
    size_t return_size = fwrite(buffer, size, nmemb, fp);
    //cout << (char *)buffer << endl;
    return return_size;
}

//http GET请求文件下载  
CURLcode dl_curl_get_req(const std::string &url, std::string filename)
{
    //int len = filename.length();
    //char* file_name = new char(len + 1);//char*最后有一个结束字符\0
    //strcpy_s(file_name, len + 1, filename.c_str());

    const char* file_name = filename.c_str();
    char* pc = new char[1024];//足够长
    strcpy(pc, file_name);

    FILE *fp = fopen(pc, "wb");

    //curl初始化  
    CURL *curl = curl_easy_init();
    // curl返回值 
    CURLcode res;
    if (curl)
    {
        //设置curl的请求头
        struct curl_slist* header_list = NULL;
        header_list = curl_slist_append(header_list, "User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko");
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, header_list);

        //不接收响应头数据0代表不接收 1代表接收
        curl_easy_setopt(curl, CURLOPT_HEADER, 0);

        //设置请求的URL地址 
        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());

        //设置ssl验证
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, false);
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, false);

        //CURLOPT_VERBOSE的值为1时，会显示详细的调试信息
        curl_easy_setopt(curl, CURLOPT_VERBOSE, 0);

        curl_easy_setopt(curl, CURLOPT_READFUNCTION, NULL);

        //设置数据接收函数
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &dl_req_reply);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);

        curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);

        //设置超时时间
        curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 6); // set transport and time out time  
        curl_easy_setopt(curl, CURLOPT_TIMEOUT, 6);

        // 开启请求  
        res = curl_easy_perform(curl);
    }
    // 释放curl 
    curl_easy_cleanup(curl);
    //释放文件资源
    fclose(fp);

    return res;
}
int main()
{
    string dl_get_url = "http://httpbin.org/#/Images/get_image_jpeg";
    string filename ="1.jpeg";
    dl_curl_get_req(dl_get_url, filename);

    cout << "下载完成！" << endl;
    getchar();
    return 0;
}

————————————————
使用上述代码需要在C/C++ 预处理器 预处理器定义中添加：
_CRT_SECURE_NO_WARNINGS

原文链接：https://blog.csdn.net/qq_37781464/article/details/102497591

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