How do I catch the event of exiting a Winforms application?

.net, c#, winforms

Solution

Check out the OnClosing event for the form.

Here is an extract from that link actually checks for a change on a text field and prompts a save:

private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
   // Determine if text has changed in the textbox by comparing to original text.
   if (textBox1.Text != strMyOriginalText)
   {
      // Display a MsgBox asking the user to save changes or abort.
      if(MessageBox.Show("Do you want to save changes to your text?", "My Application",
         MessageBoxButtons.YesNo) ==  DialogResult.Yes)
      {
         // Cancel the Closing event from closing the form.
         e.Cancel = true;
         // Call method to save file...
      }
   }
}

You can change the text to suit your needs, and then also I think you might want to switch the `DialogResult.Yes` to `DialogResult.No` based on your text.

Here is some modified code just for you:

private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
   if(MessageBox.Show("Are you sure you want to quit?", "My Application", MessageBoxButtons.YesNo) ==  DialogResult.No)
   {
      e.Cancel = true;
   }
}

Problem

If the user wants to exit the application by clicking on the exit icon or by ALT+F4, I'd like to make a dialog box questioning the user if he/she is really sure about exiting. How do I capture this event before the application is actually closed?

Original source