我的第一个计算器需要帮助

本文关键字：帮助 计算器 第一个 我的 | 更新日期: 2023-09-27 18:12:54

所以我刚开始学习编码，一直在它大约1周。我想做一个能做+和-的计算器但不知道如何让用户选择他想用的，有人能帮我吗?代码如下:

        int x;
        int y;
        Console.WriteLine("Welcome to my calculator program!");
        Console.WriteLine("This calculator for now can only do + and -");
        Console.WriteLine("If x is highter than y it will do - and if x is lower than y it will do +");
        Console.WriteLine("pls write in you x");
        x = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("pls write in your y");
        y = Convert.ToInt32(Console.ReadLine());
        if (x > y)
        {
            Console.WriteLine("you chose to use minus");
            int sum = x - y;
            Console.WriteLine("result: {0}", sum);
            Console.WriteLine("Press a key to exit");
            Console.ReadLine();
        }
        else
        {
            Console.WriteLine("you chose to use plus");
            int sum1 = x + y;
            Console.WriteLine("result: {0}", sum1);
            Console.WriteLine("Press a key to exit");
            Console.ReadLine();
        }

     }
}

}正如你所看到的，如果x I小于y，就用+，如果x大于y，就用-，这是我知道的唯一可行的方法

我的第一个计算器需要帮助

有多种可能的方法来完成您所要求的。其中最简单的是要求用户输入相应的操作符:

下面是相同的代码:

using System.IO;
using System;
class Program
{
    static void Main()
    {
        int x;
        int y;

        Console.WriteLine("Welcome to my calculator program!");
        Console.WriteLine("This calculator for now can only do + and -");
        // Reads x and y from console.
        Console.WriteLine("Enter x :");
        x = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("Enter y :");
        y = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("Enter operator for corresponding operation on x and y.'nSupported operations x - y and x + y");
        string inputOpr = Console.ReadLine(); // Stores operation to perform
        // Compares input operator to perform operation.
        if (inputOpr == "-"){
            Console.WriteLine("you chose to use minus");
            int result = x - y;
            Console.WriteLine("Result: {0}", result);
            Console.WriteLine("Press a key to exit");
            Console.ReadLine();
        }
        else if (inputOpr == "+"){
            Console.WriteLine("you chose to use plus");
            int result = x + y;
            Console.WriteLine("Result: {0}", result);
            Console.WriteLine("Press a key to exit");
            Console.ReadLine();
        }
        else{
            Console.WriteLine("Invalid Input");
        }
     }
}

天真的方法(问用户)已经得到了回答。但是你可能真正想要实现的是写一个功能齐全的计算器，用户输入一个字符串，比如2+3，程序就会给出答案。您希望编写一个解释器。

如果你考虑一下，你将不得不执行三个任务:

  • 扫描用户输入，并将其转换为一系列令牌。这是将字符串"2+3"转换为令牌系列"值为2的整数"，"加运算符"，"值为3的整数"
  • 解释令牌以计算结果

在输入上设置的约束越多(例如，正如您所说，只允许以+和-开始)，代码将越简单(如果输入不能根据您设置的规则进行解释，则会失败)。

如果你想深入了解，有很多关于这个主题的资源。我喜欢阅读这一系列的博客文章(作者使用Python，但原理保持不变)。

最后你会发现你想做的很多事情都已经完成了。已经有一些库可以解析和计算数学表达式(例如:NCalc, Mathos)。

最后，Roslyn允许您轻松解析任何c#表达式，因此它也可以用来构建一个简单的计算器，如下所示: 
class Program
{
    static void Main(string[] args)
    {
        CSharpReplAsync().Wait();
    }
    private static async Task CSharpReplAsync()
    {
        Console.WriteLine("C# Math REPL");
        Console.WriteLine("You can use any method from System.Math");
        var options = ScriptOptions.Default
            .AddImports("System", "System.Console", "System.Math");
        var state = await CSharpScript.RunAsync("WriteLine('"Hello from Roslyn'")", options);
        while (true)
        {
            Console.Write("> ");
            string expression = Console.ReadLine();
            if (string.IsNullOrEmpty(expression))
                break;
            try
            {
                state = await state.ContinueWithAsync(expression, options);
                if (state.ReturnValue != null)
                    Console.WriteLine(state.ReturnValue);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }
        }
    }
}

欢迎来到计算机程序的伟大世界。应用程序开发就是向用户提供选项并动态处理他/她的请求。因此，就像获取x和y的值一样，也可以从user获取操作符。一个简单的例子是这样的:

int x;
int y;
Console.WriteLine("Welcome to my calculator program!");
Console.WriteLine("This calculator for now can only do + and -");
Console.WriteLine("If x is highter than y it will do - and if x is lower than y it will do +");
Console.WriteLine("pls write in you x");
x = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("pls write in your y");
y = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("insert operator");
string o = Console.ReadLine();
if (o=="-")
{
    Console.WriteLine("you chose to use minus");
    int sum = x - y;
    Console.WriteLine("result: {0}", sum);
    Console.WriteLine("Press a key to exit");
    Console.ReadLine();
}
else if (o=="+")
{
    Console.WriteLine("you chose to use plus");
    int sum1 = x + y;
    Console.WriteLine("result: {0}", sum1);
    Console.WriteLine("Press a key to exit");
    Console.ReadLine();
}
else
{
    Console.WriteLine("the operator is not recognized");
}

如果你觉得有用，请在答案上做个标记。

首先让我感谢你的尝试，现在我会添加一些注释来改进代码片段。您可以使用int.TryParse进行转换，这将有助于您处理FormatExceptions，然后从用户那里获得操作员，并使用开关箱识别并根据用户输入进行操作。

将此代码作为参考，不要复制粘贴

int firstNumber, secondNumber;
Console.WriteLine("pls write in you x");
if (!int.TryParse(Console.ReadLine(), out firstNumber))
{
    Console.WriteLine("Sorry this is not an integer, 0 will be assigned");
}
Console.WriteLine("pls write in your y");
if (!int.TryParse(Console.ReadLine(), out secondNumber))
{
    Console.WriteLine("Sorry this is not an integer, 0 will be assigned");
}
/ Now you have two numbers to perform the operation
// You can now prompt the user to enter the operator
Console.WriteLine("pls enter the operator");
char operatorSign = Console.ReadKey().KeyChar;
switch (operatorSign)
{
    case '+' :
        Console.WriteLine("Result {0} + {1} = {2}", firstNumber, secondNumber, firstNumber + secondNumber);
        break;
    case '_':
        Console.WriteLine("Result {0} - {1} = {2}", firstNumber, secondNumber, firstNumber - secondNumber);
        break;
    case '*':
        Console.WriteLine("Result {0} * {1} = {2}", firstNumber, secondNumber, firstNumber * secondNumber);
        break;
    default:             
        Console.WriteLine("Sorry we are not providing this operation");
        break;
}
Console.ReadKey();

你可以这样写

    static void Main(string[] args)
    {
        int x;
        int y;
        Console.WriteLine("Welcome to my calculator program!");
        Console.WriteLine("This calculator for now can only do + and -");
        Console.WriteLine("If x is highter than y it will do - and if x is lower than y it will do +");
        Console.WriteLine("pls write in you x");
        x = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("pls write in your y");
        y = Convert.ToInt32(Console.ReadLine());
        string opt;
        int res;
        do
        {
            Console.Write("Enter your operator [+/-/:/x]:'t");
            opt= Console.ReadLine();
            res = "/+/-/:/x/".IndexOf("/" + opt + "/");
        } while (res == -1);
        double result;
        switch (opt)
        {
            case "+":
                 result= x + y;
                break;
            case "-":
                result = x - y;
                break;
            case ":":
                result = (double)x/(double)y;
                break;
            case "x":
                result = x*y;
                break;
            default:
                result = -9999;
                break;
        }
        Console.WriteLine("'n{0} {1} {2} = {3}", x, opt, y, result);
        Console.ReadLine();
    }
}
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