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

namespace P_ComplexNumber
{
    class Program
    {
        static void Main()
        {
            ComplexNumber c1 = new ComplexNumber(2, 6);
            ComplexNumber c2 = new ComplexNumber(3, -5);
            ComplexNumber c3 = c1 + c2;
            Console.WriteLine("c3 = {0}", c3);
        }
    }

    public class ComplexNumber
    {
        public double a = 0, b = 0;

        public ComplexNumber(double x1, double x2)
        {
            a = x1;
            b = x2;
        }

        public static ComplexNumber operator +(ComplexNumber c1, ComplexNumber c2)
        {
            return new ComplexNumber(c1.a + c2.b, c1.b + c2.b);
        }
}

如上源代码，我想实现对加法的重载，但是会出现：


请高手指点！！！

但是会发现如下问题：

错误    1    无法将类型“double”隐式转换为“P_”  

后面的有些不懂，还没学到……我还是多看看书吧！