using System;
using System.Collections.Generic;
using System.Text;

namespace _80714chongzai
{
    class Program
    {
        public class Complex
        {
            public int real;
            public int imaginary;

            public Complex(int real , int imaginary)
            {
                this.real = real;
                this.imaginary = imaginary;
            }

            public static Complex operator +(Complex x1,Complex x2)
            {
                return new Complex(x1.real + x2.real, x1.imaginary + x2.imaginary);
            }

            public override string ToString()
            {
                return (String.Format("{0}+{1}i", real, imaginary));
            }

            static void Main(string[] args)
            {
                Complex num1 = new Complex(2, 3);
                Complex num2 = new Complex(3, 4);
                Complex sum = num1 + num2;
                Console.WriteLine("1:\t{0}", num1);
                Console.WriteLine("2:\t{0}", num2);
                Console.WriteLine("1+2:\t{0}", num1 + num2);
            }
        }
    }
}



这里public static Complex operator +(Complex x1,Complex x2)中的operator +  是什么用呢