I'd like to know how to check out the speed of a file being uploaded in real time using the cURL library in C++. This is what I have written:

void progress_func(void* ptr, double TotalToDownload, double NowDownloaded, 
                   double TotalToUpload,double NowUploaded)
{
    cout<<NowUploaded<<endl;
}
//...
int main()
{
//...
    curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progress_func);
}

But the manual says that it shows average speed, but even this doesn't seem to work with me, because too mach fast is end.

How to good write or A well-calculated?