Adding Items To The End Of A Collection in C# & .NET

In our previous post, “Adding Items To The Beginning Of A Collection in C# & .NET”, we looked at several ways to add items to the beginning of a collection, in this case a List.

There were three techniques:

In this post, we will look at the opposite problem: how to add items to the end of a collection.

Likewise, there are also three techniques.

Insert

We can also use the Insert method here; the twist is that we need to specify where exactly to insert - the tail of the collection.

We obtain this by retrieving the number of items already in the list.

Like so:

List<int> numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

numbers.Insert(numbers.Count, 100);

Another way is to use the Append method.

List<int> numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

var newList = numbers.Append(100);

This returns a new List with the required element appended to the end.

As in the previous case, we can also use collection expressions to compose our new List.

List<int> numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

List<int> newList = [.. numbers, 100];

There are at least three ways to append elements to an existing List.

Happy hacking!