Cannot implicitly convert type void to double using using a type void method with ref parameters

Question

I'm new to C# and am having big trouble with a reference parameter (static void type) that will not return a value to my Main() method. My compiler give the this error message: cannot implicitly convert type void to double. I have researched this site (and elsewhere) for a similar problem, but was only able to find a similar case where the error message concerned implicitly converting void to int. Cannot implicitly convert type void to int

The solution that was provided involved making the method return a value band removing void from the method header.

That's where my problem starts. I am required to use a void method called CalcPrice with ref parameters. The method performs a calculation which is supposed to be returned to Main() method, but it's not working out that way. I tried to assign CalcPrice to a variable in Main() method, but that generates my error message: cannot implicitly convert type void to double.

Do you know how I can get around this??

Any help would be greatly appreciated.

Please see my code below. Thanks Peter

using System;

public class TESKDESK
{
    public static void Main()
    {
        // Declare and initialize variable for price and discount rate
        int numberOfDrawers;  
        //this variable references the OUT paramater and does not need to be   
        assigned  a value
        char typeOfWood; //this variable references the OUT paramater and does not 
        need to be assigned a value
        //int myDrawers = 0;

        //char myWood = ' ';
        double totalPrice=0;
        //discount = 0.10,
        //discountAmount;
        //GetDrawers(numberOfDrawers);

        //Call the GetDrawers() Method which prompts customer for number of drawers, 
        accepts the data entry,
        //then returns that number to the Main() method and stores it in a new 
        variable called myDrawers 
        //myDrawers = GetDrawers(numberOfDrawers);
        GetDrawers(out numberOfDrawers);


        //Call the GetWood() Method which prompts customer for their choice of desk 
        wood, accepts the data entry,
        //then returns that character to the Main() method and stores it in a new 
        variable called myWood
        //myWood = GetWoodType(typeOfWood);
        GetWoodType(out typeOfWood);
        //Console.WriteLine("You choose {0}", myWood);

        //Call the CalcPrice() Method which takes in number of drawers and desk wood 
        choosen by the customer,
        //performs a calculation with the values, then returns the final cost to a new 
        variable in Main() Method called totalPrice
        totalPrice=CalcPrice(ref numberOfDrawers, ref typeOfWood);

        DisplayResults(numberOfDrawers, typeOfWood, totalPrice);

    }

    // Create method to receive the number of desks the customer requires using the 
    OUT paramater, but the method will NOT return the value to the Main() method
    public static void GetDrawers(out int numberOfDrawers)
    {

    int myDrawers = 0;
    Console.Write("Enter the number of drawers: ");
    numberOfDrawers = Convert.ToInt16(Console.ReadLine());


    // Return result
    //return myDrawers;
    }

    //Create method to receive the customer's choice of wood product using the OUT 
paramater, but the method will NOT return the choice to the Main() method
public static void GetWoodType(out char typeOfWood)
{

    //bool acceptWoodChoice = false; //Wood product choice can be accepted
    char woodChoice = ' ';
    char pine = 'p'/*,
         oak = 'o',
         mahogany = 'm'*/;

    Console.Write("Enter the type of wood:  m, o, or p: ");
    typeOfWood = Convert.ToChar(Console.ReadLine());

    if (typeOfWood == 'p')
        Console.WriteLine("This confirms you ordered {0}", typeOfWood);
    else
        Console.WriteLine("Not recognized");


    //Create and assign values to a list of wood types



    //Return customer's choice of wood product the to the Main() method
    //return woodChoice;
    }

    //Create a method to receive drawers and wood product data entry by the REF 
 paramater and calculate price, but the method will NOT return the value to the 
Main() method
private static void CalcPrice(ref int numerOfDrawers, ref char typeOfWood)
{
    //Create and assign variables
    double totalPrice = 0;

    const double SURCHARGE = 30.00;

    if (typeOfWood == 'p')
    {
        totalPrice = (numerOfDrawers * SURCHARGE) + PINE;

    }
    /*else if (typeOfWood == 'o')
    {
        totalPrice = (numerOfDrawers * SURCHARGE) + OAK;
    }
    else
        totalPrice = (numerOfDrawers * SURCHARGE) + OTHER;*/



    //return totalPrice;

    }

     //Create a method to receive drawers and wood product data entry and calculate 
 price private static void DisplayResults(int numerOfDrawers, char typeOfWood, double 
 totalPrice)
{



    //Summarize wood product and drawers selected for customer


    if (typeOfWood == 'p')
    {
        Console.WriteLine("\nYou have ordered a Pine desk with {0} drawers", numerOfDrawers);
        Console.WriteLine("Total Cost is {0:C}\n", totalPrice);
    }




}

}

Answer 1

As the compiler is trying to tell you, CalcPrice() doesn't return anything.
totalPrice=CalcPrice(...) doesn't make any sense.

Instead, you should change the method to return double and use the return statement.
(alternatively, you could use more out parameters)

Answer 2

The part of your code that is causing the problem is where you have assigned a void method to a variable (in this case it's the "totalPrice" variable that was assigned to the CalcPrice() method: totalPrice=CalcPrice(...). The mere fact that you assigned the method to a variable means that the C# compiler expects the method to return a value; but your method can't because it's a void method. You have two options, one is to rework the method by converting it to one that returns value to the calling method, or two is to remove the assignment of your method to a variable, and then code with the assumption that your "ref variable" will be properly altered by the void method.