重载运算符

利用现有运算符，针对自定义类或结构，简化地自定义某运算操作，一般选用有相关性的既有运算符

操作数至少有一个是类或结构

不能改变运算符优先级

不能重载的运算符： =，&&，||，[],()等

class Program
    {
        static void Main(string[] args)
        {
            Pet P = new Dog("pp");
            P++;//++有了重载定义的计算方式
            P.ShowAge();
        }

    }
    abstract public class Pet
    {
        protected string Name;
        public Pet(string name)
        {
            Name = name;
        }
        public void PrintName()
        {
            Console.WriteLine("Print" + Name);
        }

       
        abstract public void Speak();
    }
   abstract public class Pet
    {
        protected string Name;
        protected int Age;
        public Pet(string name)
        {
            Name = name;
            Age = 0;
        }
        public void PrintName()
        {
            Console.WriteLine("Print" + Name);
        }
        public static Pet operator ++(Pet pet)//重载运算符++//针对类Pet
        {
            ++pet.Age;
            return pet;
        }
        public void ShowAge()
        {
            Console.WriteLine(Name+ " Age = " + Age);
        }
     
        abstract public void Speak();
    }
    public class Dog : Pet
    {
        static int Num;
        static Dog()
        {
            Num = 0;
        }
        public Dog(string name) : base(name)
        {
            ++Num;
        }
        new public void PrintName()
        {
            Console.WriteLine("子print名字是 " + base.Name);
        }
       
        {
            Console.WriteLine("子说,我是狗狗 " + Name);
        }
        static public void ShowNum()
        {
            Console.WriteLine("Dog's number = " + Num);
        }
        public void Lost()
        {
            --Num;
            Console.WriteLine(Name + " is Lost!");
        }

     
    }