How to properly exit a C# application?

问题:

I have a published application in C#. The problem here is whenever I close the main form by clicking on the red exit button, it closes the form but it doesn\'t close the application. I found this out when I tried shutting down the computer, hopeful that the application I made was running smoothly then I was bombarded by a lot of child windows with which I have put MessageBox Alerts.

I tried Application.Exit but it still calls all the child windows and alerts and I don\'t know how to use Environment.Exit and which integer to put into it. By the way, whenever my forms call the formclosed or form closing event I close the application with a this.Hide() function. Does that affect how my application is behaving now?

回答1:

From MSDN:

Application.Exit

Informs all message pumps that they must terminate, and then closes all application windows after the messages have been processed. This is the code to use if you are have called Application.Run (WinForms applications), this method stops all running message loops on all threads and closes all windows of the application.

Environment.Exit

Terminates this process and gives the underlying operating system the specified exit code. This is the code to call when you are using console application.

This article, Application.Exit vs. Environment.Exit, points towards a good tip:

You can determine if System.Windows.Forms.Application.Run has been called by checking the System.Windows.Forms.Application.MessageLoop property. If true, then Run has been called and you can assume that a WinForms application is executing as follows.

if (System.Windows.Forms.Application.MessageLoop) 
{
    // WinForms app
    System.Windows.Forms.Application.Exit();
}
else
{
    // Console app
    System.Environment.Exit(1);
}

Reference: Why would Application.Exit fail to work?

回答2:

I know this is not the problem you had, however another reason this could happen is you have a non background thread open in your application.

using System;
using System.Threading;
using System.Windows.Forms;

namespace Sandbox_Form
{
    static class Program
    {
        private static Thread thread;

        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);

            thread = new Thread(BusyWorkThread);
            thread.IsBackground = false;
            thread.Start();

            Application.Run(new Form());

        }

        public static void BusyWorkThread()
        {
            while (true)
            {
                Thread.Sleep(1000);
            }
        }
    }
}

When IsBackground is false it will keep your program open till the thread completes, if you set IsBackground to true the thread will not keep the program open. Things like BackgroundWoker, ThreadPool, and Task all internally use a thread with IsBackground set to true.

回答3:

All you need is System.Environment.Exit(1);

And it uses the system namespace \"using System\" that\'s pretty much always there when you start a project.

回答4:

By the way. whenever my forms call the formclosed or form closing event I close the applciation with a this.Hide() function. Does that affect how my application is behaving now?

In short, yes. The entire application will end when the main form (the form started via Application.Run in the Main method) is closed (not hidden).

If your entire application should always fully terminate whenever your main form is closed then you should just remove that form closed handler. By not canceling that event and just letting them form close when the user closes it you will get your desired behavior. As for all of the other forms, if you don\'t intend to show that same instance of the form again you just just let them close, rather than preventing closure and hiding them. If you are showing them again, then hiding them may be fine.

If you want to be able to have the user click the \"x\" for your main form, but have another form stay open and, in effect, become the \"new\" main form, then it\'s a bit more complicated. In such a case you will need to just hide your main form rather than closing it, but you\'ll need to add in some sort of mechanism that will actually close the main form when you really do want your app to end. If this is the situation that you\'re in then you\'ll need to add more details to your question describing what types of applications should and should not actually end the program.

回答5:

Do you do:

Application.Run(myForm);

in your Main()?

I found it a very easy way to kill the application when the form is closed.

回答6:

I would either one of the following:

Application.Exit();

for a winform or

Environment.Exit(0);

for a console application (works on winforms too).

Thanks!

回答7:

Environment.Exit(exitCode); //exit code 0 is a proper exit and 1 is an error

回答8:

In this case, the most proper way to exit the application in to override onExit() method in App.xaml.cs:

protected override void OnExit(ExitEventArgs e) {
    base.OnExit(e); 
}