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Form.OnClosing Method

Raises the Closing event.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

protected virtual void OnClosing(
	CancelEventArgs e


Type: System.ComponentModel.CancelEventArgs
A CancelEventArgs that contains the event data.

Caution noteCaution

The OnClosing method is obsolete in the .NET Framework version 2.0; use the OnFormClosing method instead.

Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.

The OnClosing method also allows derived classes to handle the event without attaching a delegate. Overriding this method is the preferred technique for handling the event in a derived class.

Caution noteCaution

The OnClosed and OnClosing methods are not called when the Application.Exit method is called to exit your application. If you have validation code in either of these methods that must be executed, you should call the Form.Close method for each open form individually before calling the Exit method.

Notes to Inheritors

When overriding OnClosing in a derived class, be sure to call the base class's OnClosing method so that registered delegates receive the event.

The following code example uses Closing to test if the text in a TextBox has changed. If it has, the user is asked whether to save the changes to a file.

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...

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.