Question

As part of my code I have created the following struct:

struct ItemInformation
{
    public int ItemNumber;
    public double HighPrice, LowPrice, MedianPrice;

    public ItemInformation(int number, double highP, double lowP) : this()
    {
        this.ItemNumber = number;
        this.HighPrice = highP;
        this.LowPrice = lowP;
        this.MedianPrice = CalculateMedian(highP, lowP);
    }

    private double CalculateMedian(double high, double low)
    {
        return 0.5 * (high + low);
    }
}

I know the struct contains four pieces of data but I want to be able to only specify three as the fourth one, MedianPrice, is completely determined by the high and low prices. So I want to use

ItemInformation jacket;

as well as

ItemInformation jacket = new ItemInformation(1234, 145.70, 73.20)

to create instances of the structure, but I cannot seem to get this to work. All the items in the struct are set correctly except for the MedianPrice. This may be a mutability issue but I am not really changing values here. I am simply setting one value based on the other two and I want to create instances of the struct using only three inputs. Does anyone have any suggestions as to how I can do this? Any advice would be greatly appreciated. Thank you.

Answer 1

You should make the struct immutable by making all instance fields readonly. Also, the MedianPrice could be a property, and it needs no data in the struct value:

struct ItemInformation
{
  public readonly int ItemNumber;
  public readonly double HighPrice, LowPrice;  // no MedianPrice here

  public ItemInformation(int number, double highP, double lowP) // no need to chain this()
  {
    this.ItemNumber = number;
    this.HighPrice = highP;
    this.LowPrice = lowP;
  }

  public double MedianPrice
  {
    get
    {
      return 0.5 * (HighPrice + LowPrice);
    }
  }
}