Add item at the beginning of each inner array in jagged array So, there is a big jagged string array (~ [120] [1 000 000]) here that represents data from an excel worksheet ( columns / rows).

Task: We have to append items at the beginning of each inner array.

I have a solution, but I am not sure about performance.

private string[][] AddField(string[][] exportDataFieldValues, string linkDisplayFieldValue)
    {
        var newExportDataFieldValues = new List&lt;string[]&gt;();
        foreach (var row in exportDataFieldValues)
        {
            var cellsRange = row.ToList();
            cellsRange.Insert(0, linkDisplayFieldValue);

            newExportDataFieldValues.Add(cellsRange.ToArray());
        }

        return newExportDataFieldValues.ToArray();
    }


Q: As you can see, my solution contains a lot of type conversions, I believe there is a more effective solution. Сan you provide a more effective solution?
I guess your code will behave very bad performance wise.
I would suggest to create the cellsRange object first as a List&lt;whatever&gt; and add 0,linkDisplayFieldValue first and then call AddRange() on cellsRange passing row.ToList() as parameter.