How to make a C# Application work as the default program for certain files? [duplicate]

Answer 1

You need to make some registry entries. First you need to associate the file extension with a class name (class name can be anything, just make it up).

So for example, if I wanted to associate .foo extensions with my Blah.exe program I would create the following registry entries (Note: In this case I'm associating .foo with a class called Foo.Document, then associated that class with my program):

Key: HKLM\SOFTWARE\Classes\.foo
Value:  = “Foo.Document”

Key: HKLM\SOFTWARE\Classes\Foo.Document
Value:  = “Foo Document”

Key: HKLM\SOFTWARE\Classes\Foo.Document\shell\open\command
Value:  = “[blah.exe]” “%1″