How to see data that post out for using libcurl at fiddler?

I would like to post data to website and I use below sample code and library to run (https://curl.haxx.se/libcurl/c/http-post.html)

I use "Telerik Fiddler Web Debugger" to monitor data that post out...but I tried many times and can't see any data at Telerik...

How to modify code or setting of Telerik that see data that post out??

Thank you for your great help!!!

Solution

You can get that data out from libcurl itself by using the CURLOPT_DEBUGFUNCTION callback. A full example using that option and some handy functions you can copy and paste exist in the debug.c example, provided in the libcurl docs.