How to make file to be opened by my app? [duplicate]

Question

This question already has answers here:

Where does Windows store its "Open With" settings? (3 answers)

Closed 8 years ago.

I have a little bit confusing problem. I'm not a beginner but I don't know how to do it.. For example I've written a program like notepad from which you can open files, save and etc. But when I set any custom format like ".blabla" to be opened by my app it is not working, so how can I make it to be opened by my app? It is in WinForms

Answer 1

You need an entry in the registry for custom file extensions. You can try inserting a key in the registry as follows:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\