code: fix2

main.cpp

@@ -52,7 +52,7 @@ download(const string& address) {
         curl_easy_setopt(curl, CURLOPT_WRITEDATA, &buffer);
         res = curl_easy_perform(curl);
         curl_easy_cleanup(curl);
-        if (!res){
+        if (res != CURLE_OK){
             curl_off_t speed;
             res1 = curl_easy_getinfo(curl, CURLINFO_SPEED_DOWNLOAD_T, &speed);
             if(!res1){