準備條件：

編譯好的libcurl庫，如果要支援https，需要和openssl一起編譯，網上教程較多

示例程式碼：

// libcurtest.cpp : 定義控制檯應用程式的入口點。
//

#include "stdafx.h"
#include <iostream>
#include <windows.h>
#include "curl.h"
using namespace std;

size_t my_write_func( void *ptr, size_t size, size_t nmemb, FILE *stream )
{
    if( stream != NULL )
        return fwrite( ptr, size, nmemb, stream );
    else
        return 0;
}

//by zhaocl
int main()
{
    HMODULE hdll = LoadLibrary( L"libcurl.dll" );

    if( !hdll )
    {
        return -1;
    }

    typedef CURL * ( *PCURL_EASY_INIT )();
    typedef CURLcode( *PCURL_EASY_SETOPT )( CURL*, CURLoption, ... );
    typedef CURLcode( *PCURL_EASY_PERFORM )( CURL* );
    typedef void( *PCURL_EASY_CLEANUP )( CURL * );

    PCURL_EASY_SETOPT pFunction = NULL;
    PCURL_EASY_PERFORM pFunction2 = NULL;
    PCURL_EASY_INIT pFunction3 = NULL;
    PCURL_EASY_CLEANUP pFunction4 = NULL;

    pFunction3 = ( PCURL_EASY_INIT )GetProcAddress( hdll, "curl_easy_init" );
    pFunction = ( PCURL_EASY_SETOPT )GetProcAddress( hdll, "curl_easy_setopt" );
    pFunction2 = ( PCURL_EASY_PERFORM )GetProcAddress( hdll, "curl_easy_perform" );
    pFunction4 = ( PCURL_EASY_CLEANUP )GetProcAddress( hdll, "curl_easy_cleanup" );

    PCURL_EASY_INIT url_ini = ( PCURL_EASY_INIT )( PCURL_EASY_INIT )GetProcAddress( hdll, "curl_easy_init" );

    if( !url_ini )
    {
        return -1;
    }

    CURL *curl;
    CURLcode res;
    //const char* strUrl = "Https://www.baidu.com";
    const char* strUrl = "https://slproweb.com/download/Win64OpenSSL-1_0_2o.exe";
    curl = url_ini();  //初始化

    if( curl && strUrl )
    {
        //下載
        FILE *outfile;
        fopen_s( &outfile, "AxTools.exe", "wb" );

        pFunction( curl, CURLOPT_URL, strUrl );
        pFunction( curl, CURLOPT_WRITEDATA, outfile );
        pFunction( curl, CURLOPT_SSL_VERIFYPEER, false ); //設定為不驗證證書和HOST
        pFunction( curl, CURLOPT_SSL_VERIFYHOST, false );
        pFunction( curl, CURLOPT_WRITEFUNCTION, my_write_func );
        pFunction( curl, CURLOPT_NOPROGRESS, FALSE );
        pFunction( curl, CURLOPT_PROGRESSFUNCTION, NULL );
        pFunction( curl, CURLOPT_PROGRESSDATA, NULL );

        res = pFunction2( curl );

        fclose( outfile );
        /* always cleanup */
        pFunction4( curl );


        //訪問
        pFunction( curl, CURLOPT_URL, strUrl );           //設定url地址

        pFunction( curl, CURLOPT_WRITEFUNCTION, my_write_func ); //設定回撥函式

        FILE *fp;
        _wfopen_s( &fp, L"c:\\test.txt", _T( "wb+" ) );
        pFunction( curl, CURLOPT_WRITEDATA, fp );      //設定寫資料

        pFunction( curl, CURLOPT_SSL_VERIFYPEER, false ); //設定為不驗證證書和HOST
        pFunction( curl, CURLOPT_SSL_VERIFYHOST, false );

        res = pFunction2( curl );                         //執行

        if( res == CURLE_OK )
        {
            //ok 處理資料
            pFunction4( curl );
            return 1;
        }

        return -1;
    }

    return -1;
}