Visual C＃ - 變量在當前上下文中不存在

我很喜歡編程c＃的初學者，公式中有兩個變量不能解析爲整數，儘管我將它們聲明爲主函數。我有多個方法實現小任務，它似乎並沒有將主變量鏈接到方法之一，其餘代碼沒有任何錯誤，所以我不知道爲什麼它沒有執行公式。（我必須張貼所有的代碼，以顯示U）Visual C＃ - 變量在當前上下文中不存在

public static void Main() 
    { 
     int income = 0; 
     int children = 0; 
     int tax = 0; 
     AskForIncome(income); 
     NoChild(children); 
     CalculateTax(tax); 
     ExitProgram(); 
    } 

    public static void AskForIncome(int income) 
    { 
     Console.WriteLine("What is your total income: "); 
     string testNum = Console.ReadLine(); 
     bool dummyBool = int.TryParse(testNum, out income); 
     if (dummyBool) 
     { 
      Console.WriteLine(); 
     } 
     else if(income < 0) 
     { 
      Console.WriteLine("Your income cannot be negative."); 
     } 
     else 
     { 
      Console.WriteLine("Enter your income as a whole-dollar numeric figure."); 
     } 
    } 
    public static void NoChild(int children) 
    { 

     Console.WriteLine("How many children do you have: "); 
     string testChild = Console.ReadLine(); 
     bool dummyBool2 = int.TryParse(testChild, out children); 
     if (dummyBool2) 
     { 
      Console.WriteLine(); 
     } 
     else if(children < 0) 
     { 
      Console.WriteLine("You must enter a positive number."); 
     } 
     else 
     { 
      Console.WriteLine("You must enter a valid number."); 
     } 

    } 
    public static void CalculateTax(int tax) 
    { 
     tax = income - 10000 - (children * 2000); 
     if (tax < 0) 
     { 
      Console.WriteLine("You owe no tax."); 
     } 
     else 
     { 
      Console.WriteLine("You owe a total of $" + tax + " tax."); 
     } 
    }

來源

2017-08-06 PotatoFries

由於int是值類型，因此您所做的是通過值傳遞，因此這些更改在主方法中不可見。有關此概念的詳細信息，請參閱https://stackoverflow.com/questions/373419/whats-the-difference-between-passing-by-reference-vs-passing-by-value。 – Smit

在c＃中，您需要使用'AskForIncome（ref int income）'來傳遞參考。 – Smit

C＃的面向對象編程語言，在你的例子看起來像你的C語言開發，所有的首先，你需要做一個類，將擁有所有的變量和函數\方法，您需要semething喜歡：

public class Employ 
{ 
    public int income {get; set;} 
    public int children {get; set} 
    public int tax {get; set}; 

      public static void AskForIncome() 
     { 
      Console.WriteLine("What is your total income: "); 
      string testNum = Console.ReadLine(); 
      bool dummyBool = int.TryParse(testNum, out income); 
      if (dummyBool) 
      { 
       Console.WriteLine(); 
      } 
      else if (income < 0) 
      { 
       Console.WriteLine("Your income cannot be negative."); 
      } 
      else 
      { 
       Console.WriteLine("Enter your income as a whole-dollar numeric figure."); 
      } 
     } 
     public static void NoChild() 
     { 

      Console.WriteLine("How many children do you have: "); 
      string testChild = Console.ReadLine(); 
      bool dummyBool2 = int.TryParse(testChild, out children); 
      if (dummyBool2) 
      { 
       Console.WriteLine(); 
      } 
      else if (children < 0) 
      { 
       Console.WriteLine("You must enter a positive number."); 
      } 
      else 
      { 
       Console.WriteLine("You must enter a valid number."); 
      } 

     } 
     public static void CalculateTax() 
     { 
      tax = income - 10000 - (children * 2000); 
      if (tax < 0) 
      { 
       Console.WriteLine("You owe no tax."); 
      } 
      else 
      { 
       Console.WriteLine("You owe a total of $" + tax + " tax."); 
      } 
     } 
}

，並從主創造聘請的對象，並盡一切你所需要的，但瞭解OOP編程這是必須的。

來源

2017-08-06 05:26:06

Visual C＃ - 變量在當前上下文中不存在

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