Develop Reference

FormClosing event fires twice after using exit button

I have a button for exiting the form and this is the code
DialogResult dialogResult = MessageBox.Show("Are you sure you want to exit?", "Exit Program?", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.No)
{
}
else
{
Application.Exit();
}
I tried using debugger mode, and after I click yes, it goes through Application.Exit() and then fires up the FormClosing event then running the same dialog.
I also tried deleting the code in FormClosing event so it only has Application.Exit() but using Alt+F4 or clicking the X button will exit the application automatically.
My question is how can I question the user if he wants to exit the program but not firing the dialog twice?
Thanks in advance, and I'm letting you all know I'm just a beginner and this is my biggest project so I want to make this great.

Here's an example. It only asks for confirmation if the close was initiated by the user - you probably don't want a MessageBox popping up when Windows is restarting.
private void form_FormClosing(object sender, FormClosingEventArgs e)
{
if (e.CloseReason == CloseReason.UserClosing)
{
DialogResult dialogResult = MessageBox.Show("Are you sure you want to exit?", "Exit Program?", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.Yes)
{
Application.Exit();
}
}
else
{
// Cancel the close
e.Cancel = true;
}
}

There are two ways to achieve this.
By unsubscribe the even on button click
As suggested in stuartd's answer, checking reason of closing (but there is a problem in his answer so adding this approach too with fix, so it will help future people.)
I am assuming, As you need this confirmation in both cases, button click and 'x' button click, you have put the same code in both handler.
Approach one
In the handler of button click, while you are asking for user confirmation and if user is clicking 'yes'.
Before the line,
Application.Exit();
you should unsubscribe the Form closing event. By doing this, It must not raise form closing event while performing Application.Exit()
assuming your form is MainForm and event is MainForm_Closing, it would look like,
private void btnClose_Click(object sender, EventArgs e)
{
DialogResult dialogResult = MessageBox.Show("Are you sure you want to exit?", "Exit Program?", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.Yes)
{
this.FormClosing -= MainForm_FormClosing;
Application.Exit();
}
}
so it will not raise form closing event while performing Application.Exit() and thus your problem will be solved.
Approach Two
As stuartd has suggested (which is more cleaner way according to me. +1 for that), you can check for form closing reason in Form Closing event handler.
Note that there is a little problem (bug) in his sample code [which you have already accepted as an answer!!]. After clicking 'x' button or Alt+F4 by mistake; if user clicks on 'No' on the confirmation message, then too form is being closed because there is no handling for else condition. Proper solution should be like below.
private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
{
if (e.CloseReason == CloseReason.UserClosing)
{
DialogResult dialogResult = MessageBox.Show("Are you sure you want to exit?", "Exit Program?", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.Yes)
Application.Exit();
else
e.Cancel = true; //stopping Form Close perocess.
}
}

C# - Override the Standard Windows Close Button to Pop-up my Custom Form

Yes, noob question. My apologies.
When users click on the red x button on the window, I want to pop up a message asking if they really would want to quit. I found a similar question on this site: Override standard close (X) button in a Windows Form.
The thing is, I want to customize the font and the MessageBoxIcon for the MessageBox, and sadly it can't be done (or will take a lot of effort to be done). So, I've decided to make my own form.
protected override void OnFormClosing(FormClosingEventArgs e)
{
if (txtID.Text != "" || txtPassword.Text != "")
{
base.OnFormClosing(e);
if (e.CloseReason == CloseReason.WindowsShutDown) return;
// Confirm user wants to close
new formConfirmExit().ShowDialog();
}
}
I added this code under the main form. However, when I run my code and I click on the standard close button, my pop up (the custom form I did) doesn't do what it's job. Suppose I click the "No" button, it terminates my entire program. With the "Yes" button, the pop-up shows up again, and then everything kinda stops (on Visual Studio) and ta-da! an exception.
BTW, these are the Yes and No button methods (from my Custom Form's class):
private void btnYes_Click(object sender, EventArgs e)
{
Application.Exit(); // terminate program (exception is in here)
}
private void btnNo_Click(object sender, EventArgs e)
{
this.Close(); // close this pop up window and go back to main window
}
Changing Application.Exit() to Environment.Exit(0) did the job for the Yes button, but my No button, well, terminates the program, still.
Edit: When I click on the Yes button, the pop-up/my custom form shows again (just one time). It'll stay on that state (I can click on the Yes button repeatedly yet nothing happens). The InvalidOperationException is thrown when I click the Yes button first (note the first sentence of this paragraph) then the No button.
Thank you.

Add this in your No_Click:
private void btnNo_Click(object sender, EventArgs e)
{
DialogResult = DialogResult.No;
}
Then, change your forms closing event to the following:
protected override void OnFormClosing(FormClosingEventArgs e)
{
if (txtID.Text != "" || txtPassword.Text != "")
{
base.OnFormClosing(e);
if (e.CloseReason == CloseReason.WindowsShutDown
|| e.CloseReason == CloseReason.ApplicationExitCall)
return;
// Confirm user wants to close
using(var closeForm = new formConfirmExit())
{
var result = closeForm.ShowDialog();
if (result == DialogResult.No)
e.Cancel = true;
}
}
}
First, it checks if the form isn't closing through Application.Exit(), this may be triggered from your other form, so it will not reshow the custom MessageBox.
Second, you create a using statement around your custom form. This way you can preserve the values. You then set the dialogresult to no, if the user doesn't want to cancel. If this is the case, set e.Cancel = true to stop from exiting.

Can't close C# application

I'm developing a C# application and when the user clicks on the X, the application gets minimized inside a trayicon. Like so:
private void frmChat_FormClosing(object sender, FormClosingEventArgs e)
{
e.Cancel = true;
Hide();
}
The application is really simple (only one form). The problem is that I can't manage to properly close the application. When the user rights clicks on the tray icon and he chooses "exit" he should be able to close the application. The problem is that even if the tray icon gets unloaded and the form is closed, the application still shows in the Task Manager as an active application. I'm closing the application like this:
private void chiudiToolStripMenuItem_Click(object sender, EventArgs e)
{
trayIcon.Dispose();
this.Close();
Application.Exit();
}
What am I missing here?

I did something similar a while back.
You need to know what is causing the form to close. So when you click on the X, there is a specific reason passed to the FormClosing event. Like so:
private void MyForm_FormClosing(object sender, FormClosingEventArgs e)
{
// don't close just yet if we click on x
if (e.CloseReason == CloseReason.UserClosing)
{
e.Cancel = true;
this.Hide();
}
}
Also, I have other code from the context menu Exit click:
private void tsmiExit_Click(object sender, EventArgs e)
{
// close the application forefully
TerminateApplication();
}
/// <summary>
/// Closes the Application.
/// </summary>
private void TerminateApplication()
{
// need to forcefully dispose of notification icon
this.notifyIcon1.Dispose();
// and exit the application
Application.Exit();
}
Edit:
Note: When you click on the X button, the close reason will be a CloseReason.UserClosing. When Application.Exit is called, the FormClosing is called again with a CloseReason.ApplicationExitCall.
End Edit:
Hope this helps
Andez

The e.Cancel = true line in frmChat_FormClosing is blocking the app from shutting down.
You can solve this easily enough by adding a boolean field to your form class, named TerminatingApp. Set this to true before calling this.Close(). Inside frmChat_FormClosing check for the value of TerminatingApp and only set e.Cancel = true if TerminatingApp is false.
Something like this:
private void frmChat_FormClosing(object sender, FormClosingEventArgs e)
{
if (!TerminatingApp)
{
e.Cancel = true;
Hide();
}
}
private void chiudiToolStripMenuItem_Click(object sender, EventArgs e)
{
TerminatingApp = true;
trayIcon.Dispose();
this.Close();
Application.Exit();
}

Ciao, how does it work if you replace Application.Exit with Application.ExitThread ?
I am actually afraid that with your code, when you call this.Close you are getting into the previous method above with the cancelling...

This is where the documentation on Application.Exit() comes in handy (my emphasis in bold):
The Exit method stops all running
message loops on all threads and
closes all windows of the application.
This method does not necessarily force the application to exit. The
Exit method is typically called from
within a message loop, and forces Run
to return. To exit a message loop for
the current thread only, call
ExitThread.

You could call Environment.Exit(0) where the parameter is the exit code.

When you are calling "this.Close" its going to call "frmChat_FormClosing" and in that you are setting "e.Cancel = true" which is creating the problem, use some variable to identify from where close event is being called and set e.Cancel accordingly.

I have tried Environment.Exit(0). It works in this case, and it worked fine for me.

Everyone else is over doing it.
Just do Close();

Why isnt my windows form closing?

Im playing about with some very simple windows forms. I have an event handler for a form close event that asks the user whether they want to save what they've typed:
private void closeNpForm(object sender, FormClosingEventArgs e)
{
if (!saveFlag)
{
if (MessageBox.Show("Do you want to save the text entered?", "Save Changes?", MessageBoxButtons.YesNo) == DialogResult.Yes)
{
e.Cancel = true;
saveFlag = true;
writeToFile(this.allText.Text);
}
}
}
if the user clicks yes (indicating they do want to save their text) i call the writeToFile method, and also set a flag so as not to ask them to save again:
private void writeToFile(string text)
{
writer = new StreamWriter("inputdata.txt");
writer.Write(text);
writer.Close();
this.Close();
}
As far as i can see, the writeToFile method should close the form when its finished. But this isnt happening, when i run the writeToFile method, the form just stays open. Can anyone tell me what im doing wrong?
as i understand it, calling this.Close() should trigger a form closing event, calling my event handler, due to the flag now being true, the form should just close without a problem.
note, my parent class extends the Form class, so im just using this to refer to my form instance.

e.Cancel = true -- whoops. The event is told cancel (read: not close the window).
I suspect that because close() is being called from within the close event and there is some internal clobbering going on (either suppressed or the Cancel is propagated over, etc). Just clean up the code (saving to the file has nothing to do with closing the window although the file might be saved and the window closed from within a button event.)
Happy coding.

writing to file and closing the form are two different kinds of operations. you should not have this.Close() in your writeToFile method.
As pst says, by setting e.cancel to true, you are basically telling the CloseForm event to be cancelled, therefore it's not closing once it exits from the closeNpForm event handler.
After exiting closeNpForm, the form checks for the Cancel property of the event and will not actually proceed with closing itself.
Why are you cancelling the close event and then calling writeToFile that closes the form?

In addition to what #pst said, why are you setting Cancel = true if you don't want to cancel the closing of the form?
If you remove e.Cancel = true; and this.Close(); it should do what you want.

This works for me:
public class Form1 : Form
{
bool saveFlag;
private void Form1_Load(object sender, EventArgs ev)
{ FormClosing += closeNpForm;
}
private void closeNpForm(object sender, FormClosingEventArgs e)
{
if (!saveFlag)
{
if (MessageBox.Show("Do you want to save the text entered?", "Save Changes?", MessageBoxButtons.YesNo) == DialogResult.Yes)
{
e.Cancel = true;
saveFlag = true;
this.Close();
}
}
}
}

How to have two versions of an event handler?

I have an event handler subscribed to the FormClosing event. This event handler provides dialog for the user when they exit my application; like so:
private void frmUavController_FormClosing(object sender, System.ComponentModel.CancelEventArgs e)
{
DialogResult dlgResult = MessageBox.Show("Are you sure you want to exit?", "Exit?",
MessageBoxButtons.YesNo, MessageBoxIcon.Question);
if (dlgResult == DialogResult.Yes)
{
UtilSTKScenario.PauseScenarioAnimation(UtilSTKScenario._stkObjectRoot);
}
else if (dlgResult == DialogResult.No)
{
e.Cancel = true;
}
}
Because the application runs in a side-by-side fashion; injecting COM commands into another application - I want my application to exit if the application receiving COM commands is not launched (or closed during execution). This is achieved like so:
static UtilSTKScenario()
{
// give time for active form to show
Thread.Sleep(100);
_stkProgramId = ConfigurationManager.AppSettings.Get("stkProgramId");
if (CheckIfStkIsLaunched())
{
InitAllFields();
}
else
{
HideController dHideController = new HideController(((frmUavController)Form.ActiveForm).HideControllerUi);
((frmUavController)Form.ActiveForm).Invoke(dHideController);
Application.Exit();
}
}
Calling 'Application.Exit()' causes the FormClosing event to fire. This I do not want - rather, I want the application to just exit.
Any ideas ?
WulfgarPro

You might be able to look at the event args of the FormClosing event. FormClosingEventArgs has a CloseReason property that may give an indicator if the form was closed by a user directly as opposed to some other mechanism.
Though I'm not clear how Application.Exit() calls will appear... If it is also showing as CloseReason.UserClosing then you may need to add an overload to your form [e.g. SystemClose()] to close your form and use an instance variable to tell it not to prompt within your handler.

Your FormClosing event gets a FormClosingEventArgs parameter, which has a CloseReason property. If that's CloseReason.ApplicationExitCall, then the form is closing because of a call to Application.Exit. You can just skip your "close?" prompt in that case.
private void frmUavController_FormClosing(object sender, FormClosingEventArgs e)
{
if (e.CloseReason == CloseReason.ApplicationExitCall)
return;
// ...

The typical way to handle this sort of thing (bypass normal "do you want to close?" checks) is to use a Boolean variable. Name it something like _forceExit, set it to true if the external event forces you to close, and if it's true, skip the dialog box in your Closing event.

Can you look at the sender object? My guess is that the sender object is different depending on you actually close the form or call the Application.Exit() method.