public class IndexerBox
{
    private string[] names = { "length", "width", "height" };
    private double[] dimensions = new double[3];

    // constructor
    public IndexerBox(double length, double width, double height)
    {
        dimensions[0] = length;
        dimensions[1] = width;
        dimensions[2] = height;
    }

    // indexer to access dimensions by integer index number
    public double this[int index]
    {
        get
        {
            // validate index to get
            if ((index < 0) || (index >= dimensions.Length))
                return -1;
            else
                return dimensions[index];
        } // end get
        set
        {
            if (index >= 0 && index < dimensions.Length)
                dimensions[index] = value;
        } // end set
    } // end numeric indexer

    // indexer to access dimensions by their string names
    public double this[string name]
    {
        get
        {
            // locate element to get
            int i = 0;
            while ((i < names.Length) &&
               (name.ToLower() != names[i]))
                ++i;

            return (i == names.Length) ? -1 : dimensions[i];
        } // end get
        set
        {
            // locate element to set
            int i = 0;
            while ((i < names.Length) &&
               (name.ToLower() != names[i]))
                ++i;

            if (i != names.Length)
                dimensions[i] = value;
        } // end set
    } // end string indexer
} // end class IndexerBox