Question

I am building a windows forms application using C# that needs to get launched when a user clicks on a file with custom extension(eg. filename.mycustomextension)
I plan to put a url in the filename.mycustomextension file. when user clicks on this file, we winform application should launch and also read contents of this file.
Is it possible to do this?

Answer 1

First and most obviously you’ll need to associate the file extension with the application either by “open with” in the shell, through an installer or directly in the registry.

MSDN – Best Practices for File Associations

Then from there it’s really pretty simple.

   static class Program
    {    
        [STAThread]
        static void Main()
        {
            string[] args = Environment.GetCommandLineArgs(); 
            string text = File.ReadAllText(args[1]);

            // ...
        }
    }

• args[0] is the application path.
• args[1] will be the file path.
• args[n] will be any other arguments passed in.

Offhand I can’t find any examples that show all of this together simply but Scott Hanselman has a nice example of loading files through a single instance WinForms application, about the same…

http://www.hanselman.com/blog/CommentView.aspx?guid=d2f676ea-025b-4fd6-ae79-80b04a34f24c