C#中类的显示类型转换和隐式类型转换

栗子

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            Stone s = new Stone(1000);
            Monkey m = (Monkey)s;
        }
    }

    class Stone
    {
        public int age;
        public Stone(int age)
        {
            this.age = age;
        }
    }

    class Monkey
    {
        public int age;
        public Monkey(int age)
        {
            this.age = age;
        }
    }
}

上述案例是通不过编译的，因为Stone和Monkey没有任何继承关系

显示类型转换操作符

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            Stone s = new Stone(1000);
            Monkey m = (Monkey)s;
            Console.WriteLine(m.age);
        }
    }

    class Stone
    {
        public int age;
        public Stone(int age)
        {
            this.age = age;
        }

        public static explicit operator Monkey(Stone s)
        {
            Monkey m = new Monkey(s.age / 100);
            return m;
        }
    }

    class Monkey
    {
        public int age;
        public Monkey(int age)
        {
            this.age = age;
        }
    }
}

可以编译和运行

隐式类型转换

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            Stone s = new Stone(1000);
            Monkey m = s;
            Console.WriteLine(m.age);
        }
    }

    class Stone
    {
        public int age;
        public Stone(int age)
        {
            this.age = age;
        }

        public static implicit operator Monkey(Stone s)
        {
            Monkey m = new Monkey(s.age / 100);
            return m;
        }
    }

    class Monkey
    {
        public int age;
        public Monkey(int age)
        {
            this.age = age;
        }
    }
}

编译运行成功