Question

I am trying to implement a string indexer for a C# class, but when you set a property the dictionary gets set and not the property. It is probably something simple that i am missing, i just can’t see it.

objFiveProp temp = new objFiveProp();
temp["index1"] = 3;

sets the temp._items[“index1”].value to 3.

Class:

public class objFiveProp
{

    #region Properties
    private Dictionary<string, int> _items;
    public int this[string key]
    {
        get { return _items[key]; }
        set { _items[key] = value; }
    }

    public int index1 { get; set; }
    public int index2 { get; set; }
    public int index3 { get; set; }
    public int index4 { get; set; }
    public int index5 { get; set; }

    #endregion
    #region Constructor

    public objFiveProp()
    {
        index1 = 0;
        index2 = 0;
        index3 = 0;
        index4 = 0;
        index5 = 0;
        _items = new Dictionary<string, int>();
        _items.Add("index1", index1);
        _items.Add("index2", index2);
        _items.Add("index3", index3);
        _items.Add("index4", index4);
        _items.Add("index5", index5);

    }

    #endregion

}

Answer 1

That’s how it works. The Dictionary contains a copy of the integers you use to set it up – not a reference to the properties.

I would tackle this by using something like:

public class objFiveProp
{
    private Dictionary<string, int> _items;
    public int this[string key]
    {
        get { return _items[key]; }
        set { _items[key] = value; }
    }

    public int Index1 
    {
        get { return this["index1"]; } 
        set { this["index1"] = value; }
    }
    public int Index2
    {
        get { return this["index2"]; } 
        set { this["index2"] = value; }
    }

    // ....

    public objFiveProp()
    {
        _items = new Dictionary<string, int>();
        _items.Add("index1", index1);
        _items.Add("index2", index2);
        _items.Add("index3", index3);
        _items.Add("index4", index4);
        _items.Add("index5", index5);    
    }

#endregion

This causes your properties to always pull the values stored in your dictionary, as well as save there, so there aren’t two copies of the values.