public delegate 返回類(lèi)型 委托名(參數(shù)類(lèi)型 參數(shù)名[, ...]);

public delegate int MathOperation(int num1, int num2);

public static int Add(int a, int b) => a + b;
public static int Subtract(int a, int b) => a - b;

MathOperation addDelegate = new MathOperation(Add);
MathOperation subtractDelegate = new MathOperation(Subtract);

MathOperation addDelegate = Add;
MathOperation subtractDelegate = Subtract;

MathOperation combinedDelegate = addDelegate + subtractDelegate;
int result = combinedDelegate.Invoke(10, 5); // 先調(diào)用Add，后調(diào)用Subtract

public class Publisher
{
    public event EventHandler<MyEventArgs> CustomEvent;

    protected virtual void OnCustomEvent(MyEventArgs e)
    {
        CustomEvent?.Invoke(this, e);
    }

    public void TriggerEvent()
    {
        OnCustomEvent(new MyEventArgs("Event triggered"));
    }
}

public class Subscriber
{
    public void Subscribe(Publisher publisher)
    {
        publisher.CustomEvent += OnCustomEvent;
    }

    private void OnCustomEvent(object sender, MyEventArgs e)
    {
        Console.WriteLine($"Subscriber received event: {e.Message}");
    }
}

public void PerformAsyncTask(Action<string> callback)
{
    Task.Run(() =>
    {
        // 模擬耗時(shí)操作
        Thread.Sleep(1000);

        // 完成任務(wù)后通過(guò)回調(diào)通知結(jié)果
        callback("Async task completed");
    });
}

// 使用回調(diào)
PerformAsyncTask(result =>
{
    Console.WriteLine($"Async task result: {result}");
});

var numbers = new[] { 1, 2, 3, 4, 5 };

// 使用Func<int, bool>作為謂詞篩選偶數(shù)
var evenNumbers = numbers.Where(n => n % 2 == 0);

// 使用Func<int, int, int>作為比較器排序
var sortedNumbers = numbers.OrderBy((a, b) => a.CompareTo(b));

MathOperation addLambda = (int a, int b) => a + b;

MathOperation addAnonymous = delegate(int a, int b) { return a + b; };