c# - 在 while 循环的第二次迭代中跳过了一段代码

Question

我有这段代码要求用户输入x和y：

do
{
    Console.Write("x = ");
    string str = Console.ReadLine();
    if (str.ToLower().Equals("exit"))
    {
        Console.WriteLine("Program has stopped");
        break;
    }
    else
    {
        while (!int.TryParse(str, out x))
        {
            Console.Write("x = ");
            str = Console.ReadLine();
        }
        while (!int.TryParse(yVal, out y))
        {
            Console.Write("y = ");
            yVal = Console.ReadLine();
        }
    }

    Console.WriteLine("Do you want to Add, Subtract, Multiply, or Divide ?");
    f = Console.ReadLine();
    if (f.ToLower().Equals("add"))
    {
        sum = x + y;
        Console.WriteLine("Result: {0}", sum);
    }
    else if (f.ToLower().Equals("subtract"))
    {
        difference = x - y;
        Console.WriteLine("Result: {0}", difference);
    }
    else if (f.ToLower().Equals("multiply"))
    {
        product = x * y;
        Console.WriteLine("Result: {0}", product);
    }
    else if (f.ToLower().Equals("divide"))
    {
        quotient = x / y;
        Console.WriteLine("Result: {0}", quotient);
    }
}
while (true);

• 它在第一次尝试时运行顺利，但
• 在第二个它询问x并跳过y直接询问

我该如何解决这个问题？

标签： c#.netloopswhile-loop