public delegate int MyDelegate(string str);//该委托可被任何一个与其且有相同标签（类型参数和返回相同类型）的方法
static void Main(string[] args)
{
//2、实例化委托
MyDelegate del = new MyDelegate(getStrLenth);
MyDelegate del2 = getStrLenth;//实例化简写
//3、调用
Console.WriteLine(del.Invoke("hello delegate!"));
Console.WriteLine(del("hello delegate!"));
//GreetingClass.GreetingChinese("中国人");
//GreetingClass.GreetingChinese("hello");
DelGreeting delGreeting = new DelGreeting(GreetingClass.GreetingEnglish);
GreetingClass.Greeting("hello", delGreeting);
Console.ReadKey();
}
public static void Greeting(string name, DelGreeting greeting)//对扩展开放，对修改封闭
{
greeting.Invoke(name);
}