c# 两个数的加减乘除

Console.Title = "加减乘除";

double x, y,z=0;
string m;
int n=0;
Console.WriteLine("第一个数：");
x = Convert.ToDouble(Console.ReadLine());
Console.WriteLine("运算符(默认为加)：");
m =Console.ReadLine();
m = (m == "加" || m == "+") ? "加" : (m == "减" || m == "-") ? "减" : (m == "乘" || m == "*"||m=="×") ? "乘" : (m == "除" || m == "/"||m=="÷") ? "除":"加" ;
Console.WriteLine("进行的是" + m + "法运算");
Console.WriteLine("第二个数：");
y = Convert.ToDouble(Console.ReadLine());

switch (m)
{
case "加":

z = x + y;
break;
case "减":

z = x - y;
break;
case "乘":

z = x * y;
break;
case "除":

z = x / y;
break;
default:

z = x + y;
break;
}

Console.WriteLine("运算结果是"+z);

Console.ReadKey();