第一个C#项目。我在错误处理方面有困难。并使用尝试/捕捉。如果有人能看一看，那就很有意义了。:)

Question

https://github.com/FaisalRana/CSharp.Bakery <--这是我回购的链接。

最近，我使用以下提示启动了一个项目:在c#中创建一个面包店，用户可以从那里订购面包或糕点。该程序根据菜单输出总价。

我正在学习测试驱动的开发，我能够成功地编写我的测试和函数，并遵循红色绿色重构工作流。

此外，通过使用if语句，我能够处理输入负数的错误。当某人输入一个字符串而不是他们的订单输入的整数时，我试图做错误处理。但

如果(输入(输入) !==整数){} <--这在c#中不起作用。在控制台中输入非int输入时所遇到的错误：

处理异常。System.FormatException: Input string was not in a correct format.

谢谢

using System;
using System.Collections.Generic;

namespace Bakery.Models
{
  public class Program
  {
    public static void Main()
    {
      Console.ForegroundColor = ConsoleColor.DarkGray;
      Console.BackgroundColor = ConsoleColor.Blue;
      Console.WriteLine("Welcome to Brother Lasif's Bakery!");
      string bakeryAscii = @"
                          ....
                      .'      `.
                    .' .-'``-._ `.
                    |  / -    - ` |
                    / |'<o>  <o> | \
                  | (|    '`    |) |
                  |   \  -==-  /   |
                  |    `.____.'    |
                  \     |    |     |
                  _\_.'`-.__.-'`._/_
                .'| |`-.  /\  .-'| |`.
              _.'   \ \  `'  `'  / /   `._
            { `.    | `-.____.-' |    .' }
            /`. `./ /   __  __   \ \.' .'\
            /   `.| |   /  \/  \   | |.'   \
          (    (  \ \  \      /  / /  )    )
            `.   \  Y|   `.  .'   |Y  /   .'
              \   \ ||_ _ _\/_ _ _|| /   /
              `.  \|'            `|/  .'
        _______/  _ >--------------< _  \______.##._
              ((((_(                )_))))   .##. |
            / ```` `--------------' ''''\   |  | |
            (                             \  |  |-'
            )                             ) `--'
            (          _        _.---.__.-'
            `-.___.--' `------'

        ";
      Console.WriteLine(bakeryAscii);
      Console.WriteLine("Please [y] to place your order, [m] to view the menu and [n] to exit");
      string  continueAnswer = Console.ReadLine().ToLower();
      if (continueAnswer == "y") {
          Console.WriteLine("How many loaves of bread would you like to purchase today?");
          int breadInput = Convert.ToInt32(Console.ReadLine()); 
            if (breadInput > 0 ) {
              Bread testBread = new Bread();
              int breadPrice = testBread.CalcBread(breadInput);
              Console.WriteLine("You have bought " + breadInput + " loaves of bread for: $" + breadPrice);
              Console.WriteLine("Would you like to buy some Pastry's today? [y] or [n]");
              string pastryAnswer = Console.ReadLine().ToLower();
              if (pastryAnswer == "y") {
                Console.WriteLine("Please enter the amount of pastry's you would like to buy:");
                int pastryInput = Convert.ToInt32(Console.ReadLine()); 
                  if (pastryInput >= 0) {
                    Pastry testPastry = new Pastry();
                    int pastryPrice = testPastry.CalcPastry(pastryInput);
                    Console.WriteLine("You have bought " + pastryInput + " pastry's");
                    Console.BackgroundColor = ConsoleColor.DarkGray;
                    Console.ForegroundColor = ConsoleColor.Green;
                    Console.WriteLine("Your total bill is $" + breadPrice + pastryPrice);
                } 
                  else {            
                  negativeNumberError();    
                } 

                  } 
                  else if (pastryAnswer == "n") {
                    Console.WriteLine("Thank you for Coming in, your total bill is $" + breadPrice);
                    Console.WriteLine("Goodbye");
                  }
  
            } else {   
              negativeNumberError();      
            }
      } else if (continueAnswer == "m") {
        Menu();
    } else if (continueAnswer == "n") {
      Console.WriteLine("Goodbye");
    } else {
      Console.WriteLine("Invalid Input");
      Main();
    }
}

    public static void Menu() {
      Console.WriteLine("--------------------------------");
        string menu = @"Fresh Bread: $5 each (loaf)
        Delicious Pastry: $2 each

        ** Special of the week **
        Bread: Buy 2, get 1 free!
        Pastry: 3 for $5!";
        Console.WriteLine(menu);
        Console.WriteLine("--------------------------------");
        Console.WriteLine("Press enter to continue");
        string menuAnswer = Console.ReadLine();
        Main();
    }
        public static void negativeNumberError() {
          Console.ForegroundColor = ConsoleColor.Red;
          Console.WriteLine("Error, please try again and enter a number greater than 0");
          Console.ReadLine();
          Main();
    }
    }
}

Answer 1

而不是

int breadInput = Convert.ToInt32(Console.ReadLine());

你可能需要类似的东西

int breadInput;
do
{
    Console.WriteLine("How many loaves of bread would you like to purchase today?");
}
while (!int.TryParse(Console.ReadLine(), out breadInput));

我选择了do...while，而不是而 (而而则更常见)，因为在评估响应之前，我们需要问这个问题。

如果我选择while，那么我将不得不重复WriteLine行。让我们来试试while

Console.WriteLine("How many loaves of bread would you like to purchase today?");

int breadInput;
while (!int.TryParse(Console.ReadLine(), out breadInput));
{
    Console.WriteLine("How many loaves of bread would you like to purchase today?");
}

这并不漂亮，但最大的问题是，有一天我可以在一个地方修改这个问题，然后忘记更新第二个WriteLine。

<1

请注意，while内部的条件可以扩展到处理负数。任何可以进入if内部的东西都可以进入while

while (!int.TryParse(Console.ReadLine(), out breadInput) || (breadInput <= 0));

辅助方法

我鼓励您创建一个可以重用的助手方法。这将使你的主要逻辑看起来清晰。下面是一个例子：

// Concise code I can reuse for multiple questions
var ok = AskPositiveInt("How many loaves of bread would you like to purchase today?"
 , max: 100
 , out int breadInput);
if(!ok) 
{
   // todo  
}

(...)

static bool AskPositiveInt(string question, int max, out int number )
{
    // Here we can add as much validation as we wish
    Console.WriteLine(question);

    int numberOfTries = 5; //Number of tries before giving up
    for( int i = 0; i < numberOfTries; i++ )
    {
        
        var answer = Console.ReadLine();

        if(!int.TryParse(answer, out number))
        {
            Console.WriteLine("Please provide a number.");
            continue; // go back to 'for'
        } 

        if (number <= 0)
        {
            Console.WriteLine("Please provide a number.");
            continue; // go back to 'for'
        }

        if (number > max)
        {
            Console.WriteLine($"Insufficient stock. Please provide a number <{max}");
            continue; // go back to 'for'
        }

        //Everything OK
        return true;
    }
    
    number = 0;
    return false;
}

错误处理

在代码中，可以在Main处理程序中调用negativeNumberError。

这不会长期有效，因为您永远不会离开原始的Main。

如果这个数字一直是负数，那么你将添加到主链->Main中。你必须想出一个更好的策略。