double.TryParse() Returns 零 (0) 不应该

Question

所以当我处理数字时，一切正常，只是当我使用非数字条目时。（我在有问题的地方评论）

当您输入任何非数字的内容时，它应该会显示一条错误消息，然后再次提示您输入有效的条目。如果您输入另一个非数字值，tryParse 不会停留在循环中，而是会将值更改为 0，从而退出循环并结束程序。我该如何解决这个问题？

我只想在输入0时退出循环，而不是触发tryParse将字符变为0的字符。

我尝试删除最后的 tryParse，但 if 语句中的第一个条件使其为假，因此直径仍然变为 0。

    static void Main()
    {
    const double MINIMUM_DIAMETER = 12.0;
    const double MAXIMUM_DIAMETER = 36.0;
    double diameter, radius, area, sliceArea;
    string userInput;

    Console.Write("\nPlease enter the diameter of your pizza: ");
    userInput = Console.ReadLine();
        do
        {
            if (double.TryParse(userInput, out diameter) == false)
            {
                Console.WriteLine("\nENTRY NON-NUMBERIC ERROR\n");
                Console.WriteLine("Pizza must have a numeric diameter. You entered: \"{0}\"\n", userInput);
                Console.WriteLine("Please try again.\n");

                //**if userInput isn't valid, diameter becomes 0**
            }
            else
            {
                if (diameter < MINIMUM_DIAMETER || diameter > MAXIMUM_DIAMETER)
                {
                    //not important
                }
                else
                {
                    //not important
                }
            }
            Console.Write("\nPlease enter the diameter of your pizza (0 to end program): ");
            userInput = Console.ReadLine();
            double.TryParse(userInput, out diameter);
            Console.Clear();

            //**if userInput isn't valid, diameter becomes 0 and exits loop**

        } while (diameter != 0);
    }

Answer 1

//if userInput isn't valid, diameter becomes 0

如果是这种情况，和

//if userInput isn't valid, diameter becomes 0 and exits loop

那么问题是您在共享内容之外将直径设置为 0？在 else 中检查 0 可以保护它免受 TryParsing arg 中的默认 0 的影响。

This link 上面是看下面的代码：

using System;

public class Program
{
    public static void Main()
    {
        string userInput;
        double diameter;
        Console.Write("\nPlease enter the diameter of your pizza: ");
        userInput = Console.ReadLine();

        while(true)
        {
            var isDouble = double.TryParse(userInput, out diameter) == true;

            if (!isDouble)
            {
                Console.WriteLine("\nENTRY NON-NUMBERIC ERROR\n");
                Console.WriteLine("Pizza must have a numeric diameter. You entered: \"{0}\"\n", userInput);
                Console.WriteLine("Please try again.\n");
                diameter = 0;
                //**if userInput isn't valid, diameter becomes 0**
            }
            else
            {
                if (diameter == 0)
                {
                    Console.Write("\n Exit initiated");
                    break;
                }
            }

            Console.Write("\nPlease enter the diameter of your pizza (0 to end program): ");
            userInput = Console.ReadLine();
            double.TryParse(userInput, out diameter);
            Console.Clear();
        }
    }
}

double.TryParse() Returns 零 (0) 不应该

double.TryParse() Returns zero (0) when it shouldn't

c#

loops

tryparse

do-while