What's the Best Way to Add One Item to an IEnumerable<T>?

Question

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

//Some IEnumerable<T> object IEnumerable<string> arr = new string[] { "ABC", "DEF", "GHI" };  //Add one item arr = arr.Concat(new string[] { "JKL" }); 

This is awkward. I don't see a method called something like ConcatSingle() however.

Is there a cleaner way to add a single item to an IEnumerable object?

Answer 1

Nope, that's about as concise as you'll get using built-in language/framework features.

You could always create an extension method if you prefer:

arr = arr.Append("JKL"); // or arr = arr.Append("123", "456"); // or arr = arr.Append("MNO", "PQR", "STU", "VWY", "etc", "...");  // ...  public static class EnumerableExtensions {     public static IEnumerable<T> Append<T>(         this IEnumerable<T> source, params T[] tail)     {         return source.Concat(tail);     } } 

Answer 2

IEnumerable is immutable collection, it means you cannot add, or remove item. Instead, you have to create a new collection for this, simply to convert to list to add:

var newCollection = arr.ToList(); newCollection.Add("JKL"); //is your new collection with the item added