委托升级

1.x
Button btn=new Button();
btn.OnClick+=new EventHandler(btn_Click);

private void btn_Click(object sender,EventArgs e)
{
}

2.0
Button btn=new Button();
btn.OnClick+=delegate(object sender,EventArgs e){};

3.0
Button btn=new Button();
btn.OnClick+=(sender,e)=>{};