將變量傳遞給另一個類，執行一個計算然後將其傳遞迴

Question

我正在嘗試編寫一個簡單的計算器，但閱讀和收聽不同的教程，我應該遵循OOP方法。試圖讓我的所有代碼都不在按鈕點擊方法中，我認爲合理的方法是以一種形式進行所有計算，例如添加除法，百分比，form1類將變量值傳遞到所有邏輯發生的計算類。但出於某種原因，總數總是等於我最後輸入的數字，而不是總數+總數。任何幫助表示讚賞。

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

     private void btnInput_Click(object sender, EventArgs e) 
     { 
      Calculations calculations = new Calculations(); 
      calculations.total = Convert.ToInt32(txtPrice.Text); 

      calculations.GetPrice(); 
      displayBox.Text = Convert.ToString(calculations.total);  
     } 
    } 
} 

計算類

class Calculations 
{ 
    public int total; 

    public int GetPrice() 
    { 
     total =+ total; 

     //See whats being stored in total 
     String totalCheck = Convert.ToString(total); 
     System.Windows.Forms.MessageBox.Show(totalCheck);      

     return total; 
    }   
} 

Answer 1

我已經制定了本辦法一個控制檯應用程序。簡單來完成它：

namespace Calculations 
{ 
    public class Program 
    { 
     private static List<Calculations> calcs = new List<Calculations>(); 

     public static void Main(string[] args) 
     { 
      Console.WriteLine("In this program you will put 10 different prices and a value will be returned."); 
      Console.WriteLine(); 
      for (int i = 0; i < 10; ++i) 
      { 
       Console.Write("Enter a price: "); 
       Calculations calc = new Calculations(int.Parse(Console.ReadLine())); 
       calc.GetPrice(); 
       calcs.Add(calc); //This is for example if you want to modify or re-access them 
      } 
     } 
    } 

    public class Calculations 
    { 
     private static Calculations instance; 
     private static int _total; 

     private static int total 
     { 
      get 
      { 
       return _total; 
      } 
      set 
      { 
       //The logic happens here. 
       instance.actsubtotal = value; 
       instance.acttotal = _total; 
       _total += value; //The single value will be summed to a stored absolute total. 
      } 
     } 

     //actsubtotal: Is the actual subtotal you entered. 
     //acttotal: Is the total that was stored in each case, if you enter for example: 
     //--- 30, 20, 50, you will have 3 instances, and the value of each acttotal will be: 30, 50, 100 
     public int actsubtotal, 
        acttotal; 

     public Calculations(int subtotal) 
     { 
      instance = this; //There is the magic, with this, you will tell the property where to find the last value. 
      total = subtotal; //Pass it as a single value (without summing it) 
     } 

     public void GetPrice() 
     { 
      Console.WriteLine("-------------"); 
      Console.WriteLine(); 
      Console.WriteLine("You actually entered: {0}", actsubtotal); 
      Console.WriteLine("Your current total is: {0}", total); 
      Console.WriteLine(); 
      Console.WriteLine("-------------"); 
     } 
    } 
} 

在這個程序，你將進入一個價格，這將是存入總，你將可以在以後再次訪問，如果你想要的。

我不知道這是否是更好的方式來做到這一點，但正如您所看到的，值存儲在稍後寫入控制檯輸出或您的情況下在MessageBox中的小計中。

通過這種方式，節省了實例的每叫你將能總結您通過使用屬性中輸入的最後一個值。

Answer 2

in GetPrice（），它應該是total += total; 不是total =+ total;。

感謝@Tipx的提醒。

因爲我的英語不好，我引用的https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/index以下描述來解釋+=和=+。

x + = y - 增量。將y的值添加到x的值中，將結果存儲在x中，並返回新值。

+ X - 返回x

沒有操作者=+的值，x =+ y意味着x = +y。

Answer 3

有一個更好的做法，可以做類，但我會遵循你的邏輯，只是爲了不讓自己感到困惑，第一件事首先從來沒有做過一個類裏面的messagebox展示（好吧，你可以但不是好的做法，無論如何，你只是用它來檢查值，但使用斷點練習）：

public partial class calculator : Form 
{ 
    public calculator() 
    { 
     InitializeComponent(); 
    } 
     //assuming this is clicking the Add (+) Button 
    private void btnInput_Click(object sender, EventArgs e) 
    { 
     double fNum = 0.0; //initialize a variable with default value 
          //if you didn't include 0.0 you will get a "local variable" error 

     Calculations calculations = new Calculations(); 
     calculations.Total = Convert.ToInt32(txtPrice.Text); 

     fNum = calculations.GetPrice(); 

     //take Note the below code will really just return the value you have just entered in your textbox since you didn't used calculations.GetPrice(); 
     //displayBox.Text = Convert.ToString(calculations.Total); 

     //the below code will show the value you have entered added 
     //to itself since the logic from your class is just Total+=Total 
     // example I input 1. (so Total = 1) then fNum will be (Total = 1 + 1) 
     // which is 2 
     displayBox.Text = Convert.ToString(fNum); 


    } 
} 



public class Calculations 
{ 
    public int Total {get; set;} //Best practice to use CamelCase for properties inside a class 

    public int GetPrice() 
    { 
     Total += Total; 

     return Total; 
    }   
}