函数——返回值不止一个的情况(解一元二次方程)

namespace 一元二次方程函数解决
{
    class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
               
            Console.WriteLine("请为一元二次方程ax²+bx+c设置相关参数：");
            Console.WriteLine("请输入a:");
            int a = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine("请输入b:");
            int b = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine("请输入c:");
            int c = Convert.ToInt32(Console.ReadLine());
            double x1=0;  //定义两个变量用来接收out的x1与x2
            double x2=0;
            string s=  new Program().solve(a,b,c,out x1,out x2);    //调用函数solve 输入参数a,b,c用来进行函数运算及 除返回值外的参数 out x1 与out x2
            Console.WriteLine(s);
            Console.WriteLine("第一个根："+x1);
            Console.WriteLine("第二个根："+x2);
            Console.ReadLine();
            }

}
        /// <summary>
        /// 解方程
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <param name="c"></param>
        /// <returns></returns>
        public string solve(int a, int b, int c,out double x1,out double x2)  //定义一个函数 用来解方程
        {
            string s;
            int x=b*b-4*a*c;
            if (a > 0 || a < 0)
            {  
                if(x>0)
                {  
                    s = "该方程有两个不等的根"; 
                }
                else if(x==0)
                {
                    s = "该方程有两个相等的根";  
                }
                else
                {
                    s = "该方程无根";
                }
            }
            else
            {
                s = "该方程无根";
            }
            x1 = (-b + Math.Sqrt(x)) / (2 * a);  //Math.Sqrt(); 求平方根
            x2 = (-b - Math.Sqrt(x)) / (2 * a);
            return s;  //返回一个string类型的s
        }
    }
}