How to prevent or block closing a WinForms window?

Question

How can I prevent window closing by showing a MessageBox? (Technology:WinForms with C#)

When the close event occurs I want the

Answer 1

private void Form1_FormClosing(object sender, FormClosingEventArgs e) {
    var window = MessageBox.Show(
        "Close the window?", 
        "Are you sure?", 
        MessageBoxButtons.YesNo);

    e.Cancel = (window == DialogResult.No);
}