如何在另一個函數中使用變量？

Question

我希望能夠在「InterestPaid」函數中使用「costOfCar」函數。我將不勝感激任何幫助。

namespace Functions9 
{ 
    class Program 
    { 
     static void Main(string[] args) 
     { 
      Double userCarCost, userDownPayment, userInterestRatePercentage, test; //declares "userCarCost" , "userDownPayment variable", "userInterestRatePercentage" 
      Console.WriteLine("This program will do some calculations for you about a car loan."); //explains the purpose and function of program to user 
      Console.WriteLine(); //adds an empty line 
      Console.WriteLine("What is the cost of your new car?"); //prompt user for input 
      userCarCost = Convert.ToDouble(Console.ReadLine()); //converts user input regarding car cost to double and stores in "userCarCost" variable 
      Console.WriteLine(); //adds an empty line 
      Console.WriteLine("How much money will you put as a down payment"); 
      userDownPayment = Convert.ToDouble(Console.ReadLine()); //converts user input regarding down payment to double and stores in "userDownPayment" variable 
      Console.WriteLine(); 
      Console.WriteLine("What is your interest rate percentage? Put a point before the number"); 
      userInterestRatePercentage = Convert.ToDouble(Console.ReadLine()); //converts user input regarding interest rate to double and stores in "userInterestRatePercentage" variable 
      Console.WriteLine(); //adds an empty line 
      Console.WriteLine("How many years before you pay back the loan?"); 

      CostOfCar(userCarCost, userDownPayment); 
     } 
     static double CostOfCar(double number1, double number2) 
     { 

      double costOfCar = number1 - number2; //"costOfCar" variable is determined by subtracting "userCarCost", "userDownPayment" 
      return costOfCar; // returns the cost of the car to the main method 
     } 

     static double InterestPaid(double number1, double number2) 
     { 
      double interestPaid = number1 * number2; 
      return interestPaid; 


     } 


    } 
} 

Answer 1

您需要一些東西來捕獲值。

在Main，而不是

CostOfCar(userCarCost, userDownPayment); 

寫入

double cost = CostOfCar(userCarCost, userDownPayment); 

這裏，變量cost被捕獲從供以後使用該函數返回的值。

Answer 2

只是叫它？

static double InterestPaid (double number1, double number2) 
    { 
     double interestPaid = number1 * number2 * CostOfCar(number1, number2); 
     return interestPaid; 
    } 

或者用你需要的正確配方。

（更新根據備註）：

static double InterestPaid (double number1, double number2) 
    { 
     var costOfCar = CostOfCar(number1, number); 
     double interestPaid = number1 * number2 * costOfCar; 
     return interestPaid; 
    } 

順便說一句，這是一個動詞，像CalculateCostOfCar更好的名稱功能。

Answer 3

static double InterestPaid (double number1, double number2) 
    {    
     var val=Program.CostOfCar(number1, number2); 
     double interestPaid = number1 * number2; 
     var total=val+interestpaid; 
     return total; 
    }