Getting verbose information from libcurl to a file - c++

Question

I am trying to develop a QT Application in C/C++ which uses libcurl. Simply, i want to save VERBOSE data to a file. In libcurl API documentation, it is said that (https://curl.haxx.se/libcurl/c/CURLOPT_VERBOSE.html)
The verbose information will be sent to stderr, or the stream set with CURLOPT_STDERR.
So, VERBOSE information will be at stderr. And after i followed the link for CURLOPT_STDERR (https://curl.haxx.se/libcurl/c/CURLOPT_STDERR.html) which tells,
Pass a FILE * as parameter. Tell libcurl to use this stream instead of stderr when showing the progress meter and displaying CURLOPT_VERBOSE data.
At the CURLOPT_STDERR link, there exists a code sample. I've tried it on my own application as:
CURL *curl = curl_easy_init();
FILE *filep = fopen("dump.txt", "wb");
if (curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://www.google.com");
curl_easy_setopt(curl, CURLOPT_STDERR, filep);
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
curl_easy_perform(curl);
}
CURLcode res = curl_easy_perform(curl);
if (CURLE_OK != res) {
fprintf(stderr, "curl told us %d\n", res);
}
curl_easy_cleanup(curl);
fclose(filep);
However, verbose information isn't shown at command line and the file which is created for the verbose information is empty. How can i solve this problem?

Answer 1

The following example works for me:
#include <stdio.h>
#include <curl/curl.h>
int main(int argc, char *argv[])
{
CURLcode ret;
CURL *hnd;
FILE* logfile;
logfile = fopen("dump.txt", "wb");
hnd = curl_easy_init();
curl_easy_setopt(hnd, CURLOPT_URL, "http://example.org");
curl_easy_setopt(hnd, CURLOPT_NOPROGRESS, 1L);
curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
curl_easy_setopt(hnd, CURLOPT_STDERR, logfile);
ret = curl_easy_perform(hnd);
curl_easy_cleanup(hnd);
fclose(logfile);
return (int)ret;
}