How do define get and set for an array data member?

Question

I am making a class Customer that has the following data members and properties:

private string customerName;
private double[] totalPurchasesLastThreeDays; //array of 3 elements that will hold the totals of how much the customer purchased for the past three days i.e. element[0] = 100, element[1] = 50, element[2] = 250

public string CustomerName
{
get { return customerName; }
set { customerName = value; }
}

public double[] TotalPurchasesLastThreeDays
{
?
}

How do I define the get and set for the array data member?

Answer 1

Do you want an indexer?

public double this[int i] {
  get { return totalPurchasesLastThreeDays[i]; }
  set { totalPurchasesLastThreeDays[i] = value; }
}

Because otherwise the question sounds a little weird, given that you already implemented a property in your code and are obviously capable of doing so.

Answer 2

You can use an auto-property:

public class Customer
{
    public string CustomerName { get; set; }

    public double[] TotalPurchasesLastThreeDays { get; set; }
}

Or if you want:

public class Customer
    {
        private double[] totalPurchasesLastThreeDays; 

        public string CustomerName { get; set; }

        public double[] TotalPurchasesLastThreeDays
        {
            get
            {
                return totalPurchasesLastThreeDays;
            }
            set
            {
                totalPurchasesLastThreeDays = value;
            }
        }
    }

And then in the constructor, you can set some default values:

public Customer()
{
    totalPurchasesLastThreeDays = new double[] { 100, 50, 250 };
}

Answer 3

You might be asking yourself this question because you think that assigning to your array is different than a regular variable?

In that case, you have to realize that when you call TotalPurchasesLastThreeDays[3] = 14.0 you are actually using the getter and not the setter. The setter is used to change the array itself and not the values it contains. So coding the getter and setter isn't any different with an array than with any other variable type.