WordPress File handle – fopen, fwrite not working with $.ajax or $.post Jquery

Hi guys. i have a problem about file handling..

Ajax is not working in fopen, fwrite etc.

please refer to this link about my problem, thanks ??

https://stackoverflow.com/questions/36619824/wordpress-file-handle-fopen-fwrite-not-working-with-ajax-or-post-jquery/

Sheldz.