c#委托详解和和示例分享

//定义委托，它定义了可以代表的方法的类型，但其本身却是一个类
 public delegate int methodDelegate(string str);

namespace ConsoleApplication1
{
    //定义委托，它定义了可以代表的方法的类型，但其本身却是一个类
    public delegate void methodDelegate(string str);
    class Program
    {
        static void Main(string[] args)
        {
            Student student = new Student();
            Teacher teacher = new Teacher("王老师");
            methodDelegate methodDelegate1 = new methodDelegate(student.getStudentName);
            methodDelegate1 += teacher.getTeacherName; //可以指向不同类中的方法！
            //methodDelegate1 += teacher.getClassName; 指向签名不符的方法时提示错误！
            methodDelegate1.Invoke("张三");
            Console.ReadLine();
        }
    }

    class Student
    {
        private String name = "";
        public Student (String _name)
        {
            this.name = _name ;
        }
        public Student() {}
        public void getStudentName(String _name)
        {
            if (this.name != "" )
                Console.WriteLine("Student's name is {0}", this.name);
            else
                Console.WriteLine("Student's name is {0}", _name);
        }
    }

    class Teacher
    {
        private String name;
        public Teacher(String _name)
        {
            this.name = _name;
        }
        public void getTeacherName(String _name)
        {
            if (this.name != "")
                Console.WriteLine("Teacher's name is {0}", this.name);
            else
                Console.WriteLine("Teacher's name is {0}", _name);
        }
        public string getClassName()
        {
            return "Eanlish";
        }
    }
}

private delegate String getAString();
static void Main(String []args)
{
    int temp = 40;
    getAString stringMethod = new getAString(temp.ToString);
    Console.WriteLine("String is {0}", stringMethod());//这里stringMethod()等价于调用temp.ToString();
    Console.ReadLine();
}

getAString stringMethod = new getAString(temp.ToString);
getAString stringMethod = temp.ToString;

getAString stringMethod = new getAString(temp.ToString);
stringMethod += temp.ToString;
stringMethod -= temp.ToString;
 

delegate double Operations(double x);

    class Program
    {
static void Main()
{
    Operations[] operations =
    {
       MathOperations.MultiplyByTwo,
       MathOperations.Square
    };

    for (int i = 0; i < operations.Length; i++)
    {
Console.WriteLine("Using operations[{0}]:", i);
DisplayNumber(operations[i], 2.0);
DisplayNumber(operations[i], 7.94);
Console.ReadLine();
    }
}

static void DisplayNumber(Operations action, double value)
{
    double result = action(value);
    Console.WriteLine(
       "Input Value is {0}, result of operation is {1}", value, result);
}
    }

    struct MathOperations
    {
public static double MultiplyByTwo(double value)
{
    return value * 2;
}

public static double Square(double value)
{
    return value * value;
}
    }