public static ThreeElements Operation(string oper)
{
ThreeElements op = null;
switch (oper)
{
case "+":
op = new AddMethod();
break;
case "-":
op = new SubMethod();
break;
case "*":
op = new MulMethod();
break;
case "/":
op = new DivMethod();
break;
}
return(op);
}
static void Main(string[] args)
{
ThreeElements p_One = new ThreeElements();
Console.WriteLine("请输入符号");
string oper = Console.ReadLine();
p_One = OperationMethod.Operation(oper);
Console.WriteLine("请输入第一个数：");
p_One.NumOne = double.Parse(Console.ReadLine());
Console.WriteLine("请输入第二个数");
p_One.NumTwo = double.Parse(Console.ReadLine());
double result = p_One.result();
Console.WriteLine("结果是：" + result);
Console.Read();
}