How can I create an ArrayList with a starting index of 1 (instead of 0)

Question

How can I start the index in an ArrayList at 1 instead of 0? Is there a way to do that directly in code?

(Note that I am asking for ArrayList

Answer 1

First, let me preface this answer by explaining my use case: Excel Interop. It's much easier to read and write data using arrays, but Excel Range.Value2 magically returns a 1 based object array.

So, if you are writing to Excel and that's the reason you are asking this question in the first place... then perhaps stop fighting c# and let Excel instantiate the array for you. So instead of:

object[,] newArray = new object[indexR, indexC];

You can use:

object[,] newArray = (object[,])RangeToWriteTo.Value2;

In my case, I created a wrapper class to allow me to use an array for the properties like so:

public abstract class ExcelRowBase
    {
        public object[,] data;

        public ExcelRowBase(int index)
        {
            data = new object[2, index + 1];
        }
    }

 public class InstanceRowModel : ExcelRowBase 
    {
        public InstanceRowModel() : base(8) 
        { 
        //constructor unique to Wire Table 
        }

        public object Configuration
        {
            get
            {
                return data[1, 1];
            }
            set
            {
                data[1, 1] = value;
            }
        }
...

So in all cases, I'm reading from the same index. So to make the transition from a model I'm passing into a Create method, I just need to copy over the properties into the model that uses the array created from Excel.

            insertingModel.data = (object[,])writeRange.Value2;

            //manually copying values from one array to the other
            insertingModel.Configuration = model.Configuration;
            ...

            writeRange.Value2 = insertingModel.data;

This works for me for now because I only have to do this in the create function. In update / get / delete, you're getting the Excel based array anyway. Perhaps a future improvement would be to create an Excel range factory that avoids the 0 based default construction all together, but this solution just gave me greens on my tests, so I'm moving on!