C#-this.Closing += new CancelEventHandler(FormMain_Closing);

Question

this.Closing += new CancelEventHandler(FormMain_Closing);这句是什么意思呢？就这句不懂。

public FormMain()
   {
   InitializeComponent();
   this.Closing += new CancelEventHandler(FormMain_Closing); //这句不懂啊
   }

   /// <summary>
   /// 关闭主窗口前的处理
   /// </summary>
   /// <param name="sender"></param>
   /// <param name="e"></param>
   void FormMain_Closing(object sender, CancelEventArgs e)
   {
   DialogResult dr = MessageBox.Show("确定退出系统吗?", "退出", MessageBoxButtons.OKCancel, MessageBoxIcon.Warning, MessageBoxDefaultButton.Button2);
   if (dr == DialogResult.OK)
   {
   //
   //在这里请处理相关事务，比如保存等
   //
   Application.Exit();
   }
   else
   {
   e.Cancel = true;
   }
   }

Answer 1

动态给 this.Closing绑定事件

Answer 2

给当前窗体添加Closing事件,事件调用FormMain窗体的Closing事件处理程序

Answer 3

+= new CancelEventHandler(FormMain_Closing);是一个委托事件，当取消的时候发生，