IF 和 Else 语句异常处理帮助 - Else 消息不起作用答案

【问题标题】：IF and Else Statement Exception Handling Help - Else message does not workIF 和 Else 语句异常处理帮助 - Else 消息不起作用
【发布时间】：2019-07-03 22:10:04
【问题描述】：

else 语句不起作用，当控制台的输入不是 Rock、Paper 或 Scissors 时，不会显示异常消息。这是什么原因。

using System;

namespace Rock__Paper__Scissors_
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Lets play a game of Rock, Paper, Scissors.");
            Console.Write("Enter Rock, Paper or Scissors:");
            string userChoice = Console.ReadLine();

            Random r = new Random();
            int computerChoice = r.Next(3);

            //0 = Scissors
            if (computerChoice == 0)
            {
                if (userChoice == "Scissors")
                {
                    Console.WriteLine("Computer chose scissors!");
                    Console.WriteLine("TIE!");
                }

                else if (userChoice == "Rock")
                {
                    Console.WriteLine("Computer chose Scissors!");
                    Console.WriteLine("You WIN!");
                }

                else if (userChoice == "Paper")
                {
                    Console.WriteLine("Computer chose Scissors");
                    Console.WriteLine("You LOSE!");

                }
            }

            //1 = Rock
            else if (computerChoice == 1)
            {
                if (userChoice == "Scissors")
                {
                    Console.WriteLine("Computer chose Rock!");
                    Console.WriteLine("You LOSE!");
                }

                else if (userChoice == "Rock")
                {
                    Console.WriteLine("Computer chose Rock!");
                    Console.WriteLine("TIE!");
                }

                else if (userChoice == "Paper")
                {
                    Console.WriteLine("Computer chose Rock");
                    Console.WriteLine("You WIN!");
                }
            }

            //2 = Paper
            else if (computerChoice == 2)
            {
                if (userChoice == "Scissors")
                {
                    Console.WriteLine("Computer chose Paper!");
                    Console.WriteLine("You WIN");
                }

                else if (userChoice == "Rock")
                {
                    Console.WriteLine("Computer chose Paper!");
                    Console.WriteLine("You LOSE!");
                }

                else if (userChoice == "Paper")
                {
                    Console.WriteLine("Computer chose Paper");
                    Console.WriteLine("TIE!");
                }
            }

            //3 = Exception Handling
            else
            {
                Console.WriteLine("You must enter Rock, Paper or Scissors");
            }


        }
    }
}

【问题讨论】：

你试过调试吗？尝试使用调试器单步执行代码。您所指的“其他”，应该说“You must enter Rock, Paper or Scissors”的那个只有当computerChoice不是0、1、2之一时才会显示。它不依赖于用户输入（Rock、Paper、Scissors）。
你在电脑的选择上有'else'
啊，好吧，这是有道理的。我会尝试一些不同的东西。谢谢。
是的...else 永远不会成功，因为computerChoice 总是介于 0 和 2 之间
你真的应该扩展“else statement doesn't work”评论

标签： c# if-statement exception

【解决方案1】：

在继续之前检查值或userChoice...我的偏好是使用while 循环

using System;

namespace Rock__Paper__Scissors_
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Lets play a game of Rock, Paper, Scissors.");
            Console.Write("Enter Rock, Paper or Scissors:");
            string userChoice = Console.ReadLine();

            //Check it here in a while loop, until the user gets it 
            //right, the program will not proceed and loop here
            while (userChoice != "Scissors" || userChoice != "Rock" || userChoice != "Paper")
            {
                Console.Write("You must enter Rock, Paper or Scissors");
                userChoice = Console.ReadLine();
            }

            Random r = new Random();
            int computerChoice = r.Next(3);

            //0 = Scissors
            if (computerChoice == 0)
            {
                if (userChoice == "Scissors")
                {
                    Console.WriteLine("Computer chose scissors!");
                    Console.WriteLine("TIE!");
                }

                else if (userChoice == "Rock")
                {
                    Console.WriteLine("Computer chose Scissors!");
                    Console.WriteLine("You WIN!");
                }

                else if (userChoice == "Paper")
                {
                    Console.WriteLine("Computer chose Scissors");
                    Console.WriteLine("You LOSE!");

                }
            }

            //1 = Rock
            else if (computerChoice == 1)
            {
                if (userChoice == "Scissors")
                {
                    Console.WriteLine("Computer chose Rock!");
                    Console.WriteLine("You LOSE!");
                }

                else if (userChoice == "Rock")
                {
                    Console.WriteLine("Computer chose Rock!");
                    Console.WriteLine("TIE!");
                }

                else if (userChoice == "Paper")
                {
                    Console.WriteLine("Computer chose Rock");
                    Console.WriteLine("You WIN!");
                }
            }

            //2 = Paper
            else if (computerChoice == 2)
            {
                if (userChoice == "Scissors")
                {
                    Console.WriteLine("Computer chose Paper!");
                    Console.WriteLine("You WIN");
                }

                else if (userChoice == "Rock")
                {
                    Console.WriteLine("Computer chose Paper!");
                    Console.WriteLine("You LOSE!");
                }

                else if (userChoice == "Paper")
                {
                    Console.WriteLine("Computer chose Paper");
                    Console.WriteLine("TIE!");
                }
            }
        }
    }
}

【讨论】：

【解决方案2】：

添加了更多 if/if else 语句而不是 else。它现在吐出我想要的异常错误。

这样做的目的是练习/应用 if、if else 和 else 方法，因为我正在尝试学习 c# 并通过一些在线教程工作。当然可能有更好的方法来制作这款游戏。

-需要添加某种循环（当我学习如何做时）。 - 计算机似乎以可预测的顺序生成随机数，而且看起来并不那么随机，所以我需要努力改进这一点。

使用系统；

namespace Rock__Paper__Scissors_
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Lets play a game of Rock, Paper, Scissors.");
            Console.Write("Enter Rock, Paper or Scissors:");
            string userChoice = Console.ReadLine();

            Random r = new Random();
            int computerChoice = r.Next(2);


            //0 = Scissors
            if (computerChoice == 0)
            {
                if (userChoice == "Scissors")
                {
                    Console.WriteLine("Computer chose scissors!");
                    Console.WriteLine("TIE!");
                }

                else if (userChoice == "Rock")
                {
                    Console.WriteLine("Computer chose Scissors!");
                    Console.WriteLine("You WIN!");
                }

                else if (userChoice == "Paper")
                {
                    Console.WriteLine("Computer chose Scissors");
                    Console.WriteLine("You LOSE!");

                }
            }

            //1 = Rock
            else if (computerChoice == 1)
            {
                if (userChoice == "Scissors")
                {
                    Console.WriteLine("Computer chose Rock!");
                    Console.WriteLine("You LOSE!");
                }

                else if (userChoice == "Rock")
                {
                    Console.WriteLine("Computer chose Rock!");
                    Console.WriteLine("TIE!");
                }

                else if (userChoice == "Paper")
                {
                    Console.WriteLine("Computer chose Rock");
                    Console.WriteLine("You WIN!");
                }
            }

            //2 = Paper
            else if (computerChoice == 2)
            {
                if (userChoice == "Scissors")
                {
                    Console.WriteLine("Computer chose Paper!");
                    Console.WriteLine("You WIN");
                }

                else if (userChoice == "Rock")
                {
                    Console.WriteLine("Computer chose Paper!");
                    Console.WriteLine("You LOSE!");
                }

                else if (userChoice == "Paper")
                {
                    Console.WriteLine("Computer chose Paper");
                    Console.WriteLine("TIE!");
                }
            }


            //Exception Handling
            if (userChoice != "Scissors")
            {
                Console.WriteLine("Choose Rock, Paper or Scissors");
            }

            else if (userChoice != "Rock")
            {
                Console.WriteLine("Choose Rock, Paper or Scissors");
            }

            else if (userChoice != "Paper")
            {
                Console.WriteLine("Choose Rock, Paper or Scissors");
            }


        }
    }
}

【讨论】：