What's the Best Way to Add One Item to an IEnumerable?

Question

Here\'s how I would add one item to an IEnumerable object:

//Some IEnumerable object
IEnumerable arr = new string[] { \"ABC\", \"DEF\"         


        

Answer 1

Since IEnumerable is read-only, you need to convert to list.

var new_one = arr.ToList().Add("JKL");

Or you can get a extension method like;

public static IEnumerable Append(this IEnumerable source, params T[] item)
{
    return source.Concat(item);
}