Question

I recently learned how to use VB.NET to set your program as the default for a chosen extension. You would write code to set a registry value. The problem is, when you open the file – after setting your program as default – it just opens your program (like a shortcut would). Is there a way that you could make it actually open the file? So say I have a text file. I set the default program for .txt files to my application. How would I make it load the text file, when I click to open the file, like you can if notepad is set to the default? If this doesn’t make sense, just let me know.

Answer 1

The path to the file is passed to your program as a command line parameter. Your program will need to read the command line parameters and react accordingly.

Here is some example code demonstrating how to read the command line parameters:

  Sub Main()
    Dim s() As String = System.Environment.GetCommandLineArgs()
    ' write code to open the file here...
    Console.WriteLine(s(1))
  End Sub

To help with debugging this you can specify command-line arguments in the Visual Studio IDE:

1. With a project selected in Solution Explorer, on the Project menu, click Properties.
2. Click the Debug tab.
3. In the Command line arguments field, enter the command-line arguments you wish to use.