Form.OnClosing Method
Assembly: System.Windows.Forms (in system.windows.forms.dll)
Caution: |
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| The OnClosing method is obsolete in the .NET Framework version 2.0; use the OnFormClosing method instead.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.
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| 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. |
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... } } }
private void Form1Closing(Object sender,
System.ComponentModel.CancelEventArgs e)
{
// Determine if text has changed in the textbox by comparing to
// original text.
if (textBox1.get_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).Equals(
get_DialogResult().Yes)) {
// Cancel the Closing event from closing the form.
e.set_Cancel(true);
// Call method to save file...
}
}
} //Form1Closing
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.
Caution: