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Question: GetSalesData: this method must get 10 sales amount values from a user. A sales amount value is seen as valid, if it can be converted to a decimal C# data type. If the value is valid, it must be stored in a one dimensinal array, which is received as an out method parameter. A count must be kept of all invalid values. This count is then returned by the method. A for loop must be used for the conversion. Note: try/catch blocks are required.

Here is my code so far but I get an error which states: Error 1 The out parameter 'sales' must be assigned to before control leaves the current method C:\Users\Asus User\Desktop\w212079735\S1P1_SalesData\S1P1_SalesData\Program.cs 34 13 S1P1_SalesData

MY CODE:

static void Main(string[] args)
       {
           decimal[] salesAmount = {};
           GetSalesData(out salesAmount);
       }

       public static int GetSalesData(out decimal []sales)
       {
           int invalidEntries = 0;
           decimal[] amounts= new decimal[10];

           for (int counter = 0; counter < amounts.Length; counter++)
           {
               try
               {
                   Console.Write("Please Enter a Sales Amount: ");
                   amounts[counter] = Convert.ToDecimal(Console.ReadLine());

               }
               catch (FormatException)
               {
                   invalidEntries++;
               }
           }
           return invalidEntries;

       }

Posted 18-Feb-13 9:29am

fatand50

Updated 18-Feb-13 11:02am

v3

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Richard C Bishop 18-Feb-13 15:34pm

I don't think you can have "[]" before a variable. []sales is not correct C# syntax.

fatand50 18-Feb-13 15:40pm

Thank you for your response, Well the thing is I want that method parameter to have values of an array that comes inside the GetSalesData method,hence I used the [ ] to indicate that the values are from only valid entries, hence on top there is an empty list that will store only valid values.

Richard C Bishop 18-Feb-13 15:42pm

In order to do that, you would simply do sales[] as you did for the decimal array. But Griff likely has the correct solution for you.

fatand50 18-Feb-13 16:00pm

Thanx, Griff gave me a solution. And I kind of now understand the whole concept.

2 solutions

Solution 2

You never assign a value to sales, or even reference it in the GetSalesData method.

You seem to be confusing an out parameter with a ref parameter with a "regular" parameter.

An out parameter passes the reference to the variable that is provided in the method call but ignores any value incoming and requires that the called method provide a value for the parameter before returning. This value will be accessable in the calling code via the passed variable. This is why you are getting the error.

A ref parameter also passes the reference to the variable that is provided in the method call but allows access to that value within the method, still allowing for the method to assign a new value to the passed variable, totally replacing the value held in the variable.

A "regular" parameter:
* for a value type (e.g., int, double, struct): the actual value of the argument is passed to the method;
* for a reference type (e.g., string, array, class): the reference to the argument object is passed to the method.

With reference types, the contents of the passed object may be manipulated and methods on the object may be called (according to the access permissions on the fields, properties, methods,... of the object).

Specifically, in your case, either:
* make the initial value in the declaration of salesAmount to be the correct size array,
remove the out from the declaration of GetSalesData and from the calling point,
add a check for sales == null (throw an ArgumentNullException),
add a check that sales.Length is large enough to hold the data,
remove the declaration of amounts,
and change the remaining usage of amounts to be sales.
OR
* change all usage of amounts to be sales,
and change the local declaration of amounts (now sales) to be a simple assignment, not a declaration.
I'd also remove the initialization of salesAmount as GetSalesData will always provide a value for it.

Further, I would not use the length of the array as the control of the loop. I'd probably have a named constant. (Unless this method will be called with different length arrays to allow for different amounts of data collected.)

Posted 18-Feb-13 10:07am

Matt T Heffron

Comments

fatand50 18-Feb-13 16:20pm

Well I hear your suggestion but at the moment I am only required to deal with Functions and Exception Handling on a book called Begining Visual C# 2010 (Chapter 6 & 7 only), and also the question is very strict that I must use out parameters. Thank you for your suggestion, I will refer back to it as we do advanced techniques.

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OriginalGriff · Accepted Answer · 2013-02-18T09:41:00

Change the name from "sales" to "amounts".
Then remove the "decimal[]" from the line:

C#

decimal[] amounts= new decimal[10];

You will end up with:

C#

public static int GetSalesData(out decimal[] amounts)
{
    int invalidEntries = 0;
    amounts= new decimal[10];

    for (int counter = 0; counter < amounts.Length; counter++)
    {
        try
        {
            Console.Write("Please Enter a Sales Amount: ");
            amounts[counter] = Convert.ToDecimal(Console.ReadLine());

        }
        catch (FormatException)
        {
            invalidEntries++;
        }
    }
    return invalidEntries;

}

And no compilation error!

It's an out parameter - you must assign a value to it before you exit the method or it won't compile!