Recently i was trying to delete a file thinking that i had closed the program which is manipulating the file but it did not delete because the program was still running. I misunderstood that file as an unwanted file. So i used the file unlocker program to find which process is manipulating that file. That program really worked well by showing the process which was handling that file. and that file was http://download.cnet.com/Unlocker/3000-2248_4-10493998.html.

What i want to know is i would like to write a program in win32 C or .net to mimic the same process. Just to find which process is handling which file. and if possible to close it.

Or i want to know the concept behind that. I know this cannot be explained in a few paragraphs yet if i could get some references or external links to references then that could be nice.