C# Delegate - DotNET | Tianciの小窝

	// 定义委托
	public delegate void MyDelegate(string message);

	// 方法 A
	public static void MethodA(string message)
	{
	Console.WriteLine($"Method A: {message}");
	}

	// 方法 B
	public static void MethodB(string message)
	{
	Console.WriteLine($"Method B: {message}");
	}

	static void Main()
	{
	MyDelegate combinedDelegate = new MyDelegate(MethodA);
	combinedDelegate += MethodB;
	combinedDelegate.Invoke("Hello, World!");
	// 输出：Method A: Hello, World!
	// Method B: Hello, World!

	combinedDelegate -= MethodB;
	combinedDelegate.Invoke("Hello, World!");
	// 输出：Method A: Hello, World!

	Console.ReadKey();
	}

	// 定义委托
	public delegate void SayHello(string userName);

	// 英文方法
	private static void EnglishSay(string userName)
	{
	Console.WriteLine("Hello!" + userName);
	}

	// 中文方法
	private static void ChineseSay(string userName)
	{
	Console.WriteLine("你好!" + userName);
	}

	// 将委托当参数传入另一个方法
	private static void Say(string userName, SayHello say)
	{
	say(userName);
	}

	static void Main()
	{
	Say("小明", EnglishSay);
	Say("小明", ChineseSay);

	Console.ReadKey();
	}

	// 定义委托
	public delegate void AnonymousDelegate(int number);

	static void Main()
	{
	AnonymousDelegate anonymous = delegate (int num)
	{
	Console.WriteLine($"Square of {num}: {num * num}");
	};

	anonymous(5); // 输出：Square of 5: 25

	Console.ReadKey();
	}

	static void Main()
	{
	Action<string> lambda = message => Console.WriteLine($"From Lambda: {message}");

	lambda("Hello from a lambda!"); // 输出：From Lambda: Hello from a lambda!

	Console.ReadKey();
	}

	// 定义一个方法给 Action
	private static void GetString(string name)
	{
	Console.WriteLine(name);
	}
	static void Main()
	{
	// Action 有参无返回值（需定义方法并调用）
	Action<string> stringAction = new Action<string>(GetString);
	stringAction("小明");

	// Action 有参无返回值（匿名方法直接调用）
	Action<string> string2Action = new Action<string>(ac =>
	{
	Console.WriteLine(ac);//ac 等于调用传参的小萌
	});
	string2Action("小萌");
	}

	static void Main()
	{
	Func<int, string> squareAndFormat = num => $"The square of {num} is {num * num}";
	string result = squareAndFormat(7);
	Console.WriteLine(result);// 输出：The square of 7 is 49
	Console.ReadKey();
	}

	// 定义一个方法给 Func
	public static bool IsNull(string text)
	{
	return string.IsNullOrEmpty(text) \|\| string.IsNullOrWhiteSpace(text);
	}
	static void Main()
	{
	// Func 有参有返回值（需定义方法并调用）
	Func<string, bool> isNullFunc = new Func<string, bool>(IsNull);
	Console.WriteLine(isNullFunc(""));

	// Func 有参有返回值（匿名方法直接调用）
	Func<string, bool> isNull2Func = new Func<string, bool>(ac =>
	{
	return string.IsNullOrEmpty(ac) \|\| string.IsNullOrWhiteSpace(ac);//ac 等于调用传参的空字符串
	});
	Console.WriteLine(isNull2Func(""));

	Console.ReadKey();
	}

	// 定义委托
	public delegate int LongRunningTaskDelegate();
	static void Main()
	{
	// 休眠两秒返回固定值
	LongRunningTaskDelegate task = () =>
	{
	Thread.Sleep(2000);
	return 66;
	};

	Console.WriteLine("开始");
	//IAsyncResult result = task.BeginInvoke(null, null);
	var waroTask = Task.Run(()=> task.Invoke());

	// 在这里执行其他任务...
	Console.WriteLine("在这里执行其他任务");

	//int returnValue = task.EndInvoke(result);
	int returnValue = waroTask.Result;
	Console.WriteLine($"Task returned: {returnValue}");

	Console.ReadKey();
	}

	// 定义事件和委托
	public class StringEventArgs : EventArgs
	{
	public string Message { get; }

	public StringEventArgs(string message)
	{
	Message = message;
	}
	}

	public delegate void MessageEventHandler(object sender, StringEventArgs e);

	// 引发事件
	public class EventPublisher
	{
	// 定义事件
	public event MessageEventHandler MessageReceived;

	protected virtual void OnMessageReceived(StringEventArgs e)
	{
	MessageReceived?.Invoke(this, e);
	}

	public void SendMessage(string message)
	{
	var args = new StringEventArgs(message);
	OnMessageReceived(args);
	}
	}

	// 订阅和取消订阅事件
	public class EventSubscriber
	{
	public void Subscribe(EventPublisher publisher)
	{
	publisher.MessageReceived += OnMessageReceived;
	}

	public void Unsubscribe(EventPublisher publisher)
	{
	publisher.MessageReceived -= OnMessageReceived;
	}

	private void OnMessageReceived(object sender, StringEventArgs e)
	{
	Console.WriteLine($"Subscriber received message: {e.Message}");
	}
	}

	// 调用
	static void Main()
	{
	var publisher = new EventPublisher();
	var subscriber = new EventSubscriber();

	subscriber.Subscribe(publisher);
	publisher.SendMessage("Hello, world!");

	subscriber.Unsubscribe(publisher);
	publisher.SendMessage("Hello, world!");

	Console.ReadKey();
	}

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