I'm trying to assign to a variable the unique index that is in $\_POST.

I'm trying to do this, because the $\_POST value will change for each button I press, and doing them all is like too long, plus, it's like a filer, every time you add a file, 3 new buttons appear, so too long.

The value either starts with 'edit', 'download', or 'delete', followed by the id of the selected file. For example, the 8th file will be deleted with 'delete8'.

I used filter to fetch the file id in my php file, but I can do it, only when I know exactly how the value is named. 

Is there a way to select automatically the one and only value available in $\_POST ?