How do I show a MessageBox prompt when the user has clicked the cross in the title bar

Question

I am currently developing a C# Windows Form Application.

After the user has login through the loginForm, it will be brought to the mainForm.

I would like to code it in a way that after the user click the cross on the title bar in the mainForm, there would be a prompt asking the user "This will close the application. Confirm?" followed by a yes and no button.

If yes, another box will be displayed, "Application Closed!"

If no, the messagebox will just close and the application will continue running.

My current code is :

private void mainForm_FormClosing(object sender, FormClosingEventArgs e)
{
    if (MessageBox.Show("This will close down the whole application. Confirm?", "Close Application", MessageBoxButtons.YesNo) == DialogResult.Yes)
    {
        MessageBox.Show("The application has been closed successfully.", "Application Closed!", MessageBoxButtons.OK);
        System.Windows.Forms.Application.Exit();
    }
    else
    {
        this.Activate();
    }   
}

however it does not work.

Firstly I have no idea why the messagebox pops up twice in order for the whole thing to close.

Secondly if i click no, the form closes as well and I am not able to bring it back.

Answer 1

To cancel the closing of the form, in your else statement you need e.Cancel = true;. You don't need the explicit Exit in your true case.

Give this a try

private void mainForm_FormClosing(object sender, FormClosingEventArgs e)
{
    if (MessageBox.Show("This will close down the whole application. Confirm?", "Close Application", MessageBoxButtons.YesNo) == DialogResult.Yes)
    {
        MessageBox.Show("The application has been closed successfully.", "Application Closed!", MessageBoxButtons.OK);

    }
    else
    {
        e.Cancel = true;
        this.Activate();
    }   
}

I assume your second MessageBox to say it has closed if for testing purposes only.

You probably only want.

private void mainForm_FormClosing(object sender, FormClosingEventArgs e)
{
    if (MessageBox.Show("This will close down the whole application. Confirm?", "Close Application", MessageBoxButtons.YesNo) != DialogResult.Yes)
    {
        e.Cancel = true;
    } 
}

Notice the statement checks to see if they didn't hit yes, rather than if they hit cancel. This means that if they hit the x on the dialog box it won't be counted as a confirmation.

EDIT: If mainForm isn't the main form

Okay, I think I've got what you're asking now.

What I would do is put the code I have in my second code block above in the FormClosing, and then in the FormClosed event handler have this

private void mainForm_FormClosed(Object sender, FormClosedEventArgs e)
{
    MessageBox.Show("The application has been closed successfully.", "Application Closed!", MessageBoxButtons.OK);
    System.Windows.Forms.Application.Exit();
}

Answer 2

This should help you

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        if (MessageBox.Show("Are you sure you want to close?", "Close", MessageBoxButtons.YesNo) == System.Windows.Forms.DialogResult.No)
            e.Cancel = true;
    }