winform 系统关闭前提示

        private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (MessageBox.Show("您确定退出系统吗?", "系统提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
            {
                e.Cancel = false;
            }
            else
            {
                e.Cancel = true;
            }

        }