C#关于Func和Action委托的介绍详解

/// <summary>
/// 不包含参数
/// </summary>
private event Action Action_0;
/// <summary>
/// 包含一个参数
/// </summary>
private event Action<int> Action_1;
/// <summary>
/// 包含两个参数
/// </summary>
private event Action<int, double> Action_2;
/// <summary>
/// 包含三个参数
/// </summary>
private event Action<int, double, string> Action_3;

/// <summary>
/// 定义没有参数委托的事件
/// </summary>
private void Fun_0()
{
    Console.WriteLine("没有参数");
}
/// <summary>
/// 定义包含一个参数委托的事件
/// </summary>
private void Fun_1(int nInt)
{
    Console.WriteLine($"包含一个参数：{nInt}");
}
/// <summary>
/// 定义包含两个参数委托的事件
/// </summary>
private void Fun_2(int nInt, double dDouble)
{
    Console.WriteLine($"包含两个参数，参数值：{nInt}，{dDouble}");
}
/// <summary>
/// 定义包含三个参数委托的事件
/// </summary>
private void Fun_3(int nInt, double dDouble, string str)
{
    Console.WriteLine($"包含三个参数，参数值：{nInt}，{dDouble}，{str}");
}


//点击事件
private void btn_Click(object sender, EventArgs e)
{
    //向委托添加事件
    Action_0 += Fun_0;
    Action_1 += Fun_1;
    Action_2 += Fun_2;
    Action_3 += Fun_3;

    //执行委托
    Action_0.Invoke();
    Action_1.Invoke(666);
    Action_2.Invoke(666,888.0);
    Action_3.Invoke(666,888,"Hello World");
}

private void button1_Click(object sender, EventArgs e)
{
    Action_0?.Invoke();
    Action_1?.Invoke(666);
    Action_2?.Invoke(666, 888.0);
    Action_3?.Invoke(666, 888, "Hello World");
}

//执行委托
private void button1_Click(object sender, EventArgs e)
{
    try
    {
        Action_0.Invoke();
        Action_1.Invoke(666);
        Action_2.Invoke(666, 888.0);
        Action_3.Invoke(666, 888, "Hello World");
    }
    catch (Exception ex)
    {
        MessageBox.Show("调用出现异常", "提示");
    }
}

public partial class Form1 : Form
{

    /// <summary>
    /// 包含两个参数int和double，返回值为string类型委托
    /// </summary>
    private event Func<int, double, string> TestFunc;

    /// <summary>
    /// 定义委托的事件
    /// </summary>
    private string Fun_1(int nInt, double dDouble)
    {
        Console.WriteLine($"参数值：{nInt}，{dDouble}");
        return "事件：Fun_1";
    }
    /// <summary>
    /// 定义委托的事件
    /// </summary>
    private string Fun_2(int nInt, double dDouble)
    {
        Console.WriteLine($"参数值：{nInt}，{dDouble}");
        return "事件：Fun_2";
    }

    /// <summary>
    /// 窗体构造函数
    /// </summary>
    public Form1()
    {
        InitializeComponent();
        InitAction();
    }

    //向委托添加事件
    private void InitAction()
    {
        TestFunc += Fun_1;
        TestFunc += Fun_2;
    }

    //执行委托
    private void button1_Click(object sender, EventArgs e)
    {
        var result = TestFunc?.Invoke(888, 10);
        Console.WriteLine($"返回结果：{result}");
    }

}