C＃计算器类

Question

我接到了这个家庭作业，我一直很难过。表格是写的，我们必须写课。目前，当我运行程序时，我的等号按钮似乎不起作用。我不确定为什么，我想知道是否有人可以帮助我理解我所缺少的东西。我相信我已经正确地写了我的课。在我脑海中，正在发生的事情是计算器正在调用“currentValue”，因此我不断使用我在运算符中使用的方法进行更新。

我是朝着正确的方向吗？

为什么我的等号按钮不是调用当前值。我最后一次运行它，如果我键入9 + 3 +然后我的显示器将填充12并等待我输入下一个数字。所以在理论上为什么我的等号按钮不会加载答案？我相信我正在调用正确的项目，但我一直在初次进入。例如，如果我键入9 + 9并且命中=我一直得到9。

这是计算器代码（提供的部分）：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Calculator
{
public partial class frmCalculator : Form
{
    public frmCalculator()
    {
        InitializeComponent();
    }

    // The following fields are used to store the value that's currently
    // displayed by the calculator. displayString is a string value that's
    // constructed as the user clicks numeric keys and the decimal and +/-
    // key. The Convert.ToDecimal method is then used to convert this to a decimal
    // field that's stored in displayValue.
    private string displayString;
    private decimal displayValue;

    // The following bool fields are used to control numeric entry.
    // newValue indicates whether the calculator is ready to receive a
    // new numeric value. Once the user clicks a digit button, newValue is
    // set to false. When the user clicks a button that "enters" the value, 
    // such as Add or Equals, newValue is set to true so the user can enter 
    // another value.
    // decimalEntered is used to restrict the entry to a single decimal point.
    // It is set to true whenever newValue is set to true, and it is set to 
    // false whenever the user clicks the decimal point button.
    private bool newValue;
    private bool decimalEntered;

    private Calculator calc = new Calculator();

    private void Form1_Load(object sender, System.EventArgs e)
    {
        displayValue = 0;
        displayString = displayValue.ToString();
        newValue = true;
        decimalEntered = false;
    }

    // This method handles the 0 through 9 keys, appending the digit clicked
    // to the displayString field. 
    private void btnNumber_Click(object sender, System.EventArgs e)
    {
        if (newValue)
        {
            displayString = "";
            newValue = false;
        }
        displayString += ((Button)sender).Tag.ToString();
        displayValue = Convert.ToDecimal(displayString);
        txtDisplay.Text = displayValue.ToString();
    }

    // This method removes the last character from the displayString field.
    private void btnBackSpace_Click(object sender, System.EventArgs e)
    {
        if (displayString.Length > 1)
        {
            displayString = displayString.Substring(0, displayString.Length - 1);
            displayValue = Convert.ToDecimal(displayString);
            txtDisplay.Text = displayValue.ToString();
        }
        else
        {
            displayString = "";
            displayValue = 0;
            txtDisplay.Text = displayValue.ToString();
        }

    }

    private void btnClear_Click(object sender, System.EventArgs e)
    {
        calc.Clear();
        displayString = "";
        displayValue = 0;
        txtDisplay.Text = displayValue.ToString();
        newValue = true;
        decimalEntered = false;
    }

    // This method appends a decimal point to the displayString field if the
    // user has not already entered a decimal point.
    private void btnDecimal_Click(object sender, System.EventArgs e)
    {
        if (newValue)
        {
            displayString = "0";
            newValue = false;
        }
        if (!decimalEntered)
        {
            displayString += ".";
            displayValue = Convert.ToDecimal(displayString);
            txtDisplay.Text = displayValue.ToString();
            decimalEntered = true;
        }
    }

    private void btnSign_Click(object sender, System.EventArgs e)
    {
        displayValue = -displayValue;
        txtDisplay.Text = displayValue.ToString();
    }

    private void btnAdd_Click(object sender, System.EventArgs e)
    {
        calc.Add(displayValue);
        newValue = true;
        decimalEntered = false;
        displayValue = calc.CurrentValue;
        txtDisplay.Text = displayValue.ToString();
    }

    private void btnSubtract_Click(object sender, System.EventArgs e)
    {
        calc.Subtract(displayValue);
        newValue = true;
        decimalEntered = false;
        displayValue = calc.CurrentValue;
        txtDisplay.Text = displayValue.ToString();
    }

    private void btnMultiply_Click(object sender, System.EventArgs e)
    {
        calc.Multiply(displayValue);
        newValue = true;
        decimalEntered = false;
        displayValue = calc.CurrentValue;
        txtDisplay.Text = displayValue.ToString();
    }

    private void btnDivide_Click(object sender, System.EventArgs e)
    {
        calc.Divide(displayValue);
        newValue = true;
        decimalEntered = false;
        displayValue = calc.CurrentValue;
        txtDisplay.Text = displayValue.ToString();
    }

    private void btnSqrt_Click(object sender, System.EventArgs e)
    {
        calc.SquareRoot(displayValue);
        displayValue = calc.CurrentValue;
        txtDisplay.Text = displayValue.ToString();
    }

    private void btnReciprocal_Click(object sender, System.EventArgs e)
    {
        try
        {
            calc.Reciprocal(displayValue);
            displayValue = calc.CurrentValue;
            txtDisplay.Text = displayValue.ToString();
        }
        catch (DivideByZeroException)
        {
            displayValue = 0;
            txtDisplay.Text = "Cannot divide by zero.";
            newValue = true;
            decimalEntered = false;
        }
    }

    private void btnEquals_Click(object sender, System.EventArgs e)
    {
        try
        {
            if (newValue)
                calc.Equals();
            else
                calc.Equals(displayValue);
            displayValue = calc.CurrentValue;
            txtDisplay.Text = displayValue.ToString();
            newValue = true;
            decimalEntered = false;
        }
        catch (DivideByZeroException)
        {
            displayValue = 0;
            txtDisplay.Text = "Cannot divide by zero.";
            newValue = true;
            decimalEntered = false;
        }
    }

}

}

这是我的课（我写的部分）：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Calculator
{
public class Calculator
{

    public Decimal displayValue;
    public Decimal currentValue;

     public void Add(Decimal displayValue)
    {

        currentValue += displayValue;

    }

     public void Subtract(Decimal displayValue)
     {
         currentValue -= displayValue;
     }

     public void Multiply(Decimal displayValue)
     {
         currentValue *= displayValue;
     }


     public void Divide(Decimal displayValue)
     {
         currentValue /= displayValue;
     }

     public void SquareRoot(Decimal displayValue)
     {
         currentValue = (decimal)Math.Sqrt(Convert.ToDouble(displayValue));
     }

     public void Reciprocal(Decimal displayValue)
     {
         currentValue = 1 / displayValue;
     }

     public decimal Equals()
     {
         return currentValue;
     }


     public void Clear()
     {
         currentValue = 0;
         displayValue = 0;
     }

     public decimal CurrentValue
     {
       get
          {
           return currentValue;
          }

     }
}

}

Answer 1

在主代码中，您调用了Equal（）方法，如下所示：

if (newValue)
    calc.Equals();
else
    calc.Equals(displayValue); //Your class do not have this.

所以，你应该先做这个

//I am not sure why you need to pass in the displayValue parameter, so I presume it would not return anything.
public void Equal(Decimal displayValue)
{
        //Do the things you suppose to do
}

对于你的9 + 9 = 9问题，这只是因为在你的代码中，你只需按下你的点击事件Add_Button一次。在Add()方法上设置一个断点。然后尝试这样做：

9 - ＆gt;按下你的Add_Button - ＆gt; 9 - ＆gt;按下你的Add_Button - ＆gt;检查你的currentValue

Answer 2

displayValue既是类字段又是方法参数。这是你的意图吗？分配给字段参数时，您需要设置this.displayValue = ...，以便明确您正在执行的操作。目前，您正在覆盖参数的本地副本，字段值始终为0.

只需删除decimal displayValue;声明（以及Clear()函数），然后将displayValue存储在表格的类外。

public class Calculator
{

    //public Decimal displayValue;
    public Decimal currentValue;

    public void Add(Decimal displayValue)
    {

        currentValue+=displayValue;

    }
    ...
    public void Clear()
    {
        currentValue=0;
        //displayValue=0;
    }

    public decimal CurrentValue
    {
        get { return currentValue; }

    }
}

class Program
{
    static void Main(string[] args)
    {
        Calculator calc=new Calculator();
        calc.Add(1000m);
        calc.Divide(25m);
        calc.Subtract(8m);

        Console.WriteLine(calc.CurrentValue);
        // (1000/25)-8 = 32
    }
}

Answer 3

我在你的代码中看到的主要问题是你只添加了一个操作数，所以例如8 + 8总是等于8。你必须做这样的事情（仅包括Add和倒数函数） ：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Calculator
{
public class Calculator
{

    public Decimal displayValue;
    public Decimal currentValue;

    private Decimal Operand_1;
    private Decimal Operand_2;

    private bool Operand_1_Added = false;
    private bool Operand_2_Added = false;

    private string Operation = "";

   private void AddOperand(Decimal Operand)
    {
            if(Operand_1_Added) 
                {
                  Operand_2 = Operand;
                  Operand_2_Added = true;
                }
            else {
                  Operand_1 = Operand;
                  Operand_1_Added = true;
                  currentValue = Operand_1;
                 }
     }



   public void Add(Decimal Arg1)
    {  
        this.AddOperand(Arg1);
        Operation = "Addition";
    }

   public void Reciprocal(Decimal Arg)
    {
     this.AddOperand(Arg);
     Operation = "Reciprocal";
    }


     public void Clear()
     {
         currentValue = 0;
         displayValue = 0;
         Operand_1 = 0;
         Operand_2 = 0;
     }

     public void Equals()
      {
         switch(Operation)
             {
                 case "Addition": 
                          currentValue = Operand_1 + Operand_2;
                          break;
                 case "Reciprocal":
                          currentValue = 1/Operand_1;
                          break;
                 default: break; 
              }
      }

   public void Equal(Decimal displayValue)
   {
    currentValue = displayValue;
   }
     public decimal CurrentValue
     {
       get
          {
           return currentValue;
          }

     }
}

尚未测试代码，但这应该适用于表单类。

Answer 4

让我们来看看要求：

“乘法结果应显示的小数位数不得超过第一个数字的结果而不是第二个数字。例55.5 * 89.68 = 4977.240”

基本算术中乘法的自然意味着无论如何都会发生这种情况。例如。你永远不会将X.X乘以X.XX并获得结果X.XXXXXXX ...... - 它不可能发生。

格式化很容易 - 如果你需要显式格式化然后格式化为num.ToString（“＃。##############”），它允许一堆数字。< / p>

您尚未对部门提出任何要求，因此我无法发表评论。

顺便说一句 - 如果你说x = 1/3和y = z * x，那么你将在小数位后得到很多数字，因为x是.333333333 ...开头。这符合AFAICT的要求。