Question

I’m having trouble understanding how to close an C# .NET winforms application. What I’m trying to do is:

Display a form to allow the user to set-up the environment how they want
If the user presses the “OK” button, perform some logic for setting up the application environment (instantiate objects, etc)
If the user presses “Cancel” or closes the window, close the application.

The problem is, I’m calling the environment set-up form before the main (1st) form. It’s a recent requirement change, and I didn’t fancy re-writing the code that I have from the very beginning.

The code I have (which should make more sense than my little preamble) is:

    public MainForm()
    {
        InitializeComponent();
        //Get the user to set-up the environment (load specific config files, etc)

        environmentSetupForm newEnvrionmenSetupForm = new environmentSetupForm ();
        if (newEnvrionmenSetupForm .ShowDialog() == DialogResult.OK)
        {
            newEnvrionmenSetupForm .Close();
            //some logic based on what the user selected on the set-up form
        }
        else
        {
            //Since the user didn't set-up the environment correctly (there
            //was a message box, informing them and giving them another
            //shot at it), exit out of the application.
            Application.Exit();
        }
    }

My only problem is that after Application.Exit(), the stack jumps back to Program.cs and performs

        Application.Run(new MainForm());

So the Main form (and app) runs regardless. Is there a better way to do what I’m trying to do?

Edit: for clarity my program.cs code reads:

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Windows.Forms;

   namespace myNamespace
   {
      static class Program
      {
      /// <summary>
      /// The main entry point for the application.
      /// </summary>
      [STAThread]
        static void Main()
        {
          Application.EnableVisualStyles();
          Application.SetCompatibleTextRenderingDefault(false);
          Application.Run(new MainForm());
        }
     }
   }

Answer 1

Neither the form’s constructor nor its OnLoad or Load event are good places to put this code. The constructor runs due to the new MainForm() statement in the Main() method, before the Application.Run() call. The Load event is fired because the Application class calls the Show() method, hidden inside the framework code just before Application.Run() enters the message loop. Application.Exit() cannot do anything until that message loop starts running.

The workaround is to move this code to the Main() method in Program.cs. Make it look similar to this:

    [STAThread]
    static void Main() {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        MainForm main;            
        using (var dlg = new environmentSetupForm()) {
            if (dlg.ShowDialog() != DialogResult.OK) return;
            // Use dlg values
            //...
            main = new MainForm();
            // Make main form show up at the same location
            main.StartPosition = FormStartPosition.Manual;
            main.Location = dlg.Location;
        }
        Application.Run(main);
    }