MSDNから直接:
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...
}
}
}
あなたの場合、フォームを明示的に閉じるために何もする必要はありません。キャンセルしない限り、自動的に閉じられるため、コードは次のようになります。
private void addFile_FormClosing( object sender, FormClosingEventArgs e ) {
var closeMsg = MessageBox.Show( "Do you really want to close?", "Warning", MessageBoxButtons.YesNo, MessageBoxIcon.Question );
if (closeMsg == DialogResult.Yes) {
// do nothing
} else {
e.Cancel = true;
}
}