C# 4 and .NET 4

230 ❘ ChaPTer 10 cOllectiOns
inserting elements
You can insert elements at a specifi ed position with the Insert() method:
racers.Insert(3, new Racer(6, "Phil", "Hill", "USA", 3));
The method InsertRange() offers the capability to insert a number of elements, similarly to the
AddRange() method shown earlier.
If the index set is larger than the number of elements in the collection, an exception of type ArgumentOutOf
RangeException is thrown.
accessing elements
All classes that implement the IList and IList < T > interface offer an indexer, so you can access the elements
by using an indexer and passing the item number. The fi rst item can be accessed with an index value
0. By specifying racers[3] , you will access the fourth element of the list:
Racer r1 = racers[3];
Getting the number of elements with the Count property, you can do a for loop to iterate through every
item in the collection, and use the indexer to access every item:
for (int i = 0; i < racers.Count; i++)
{
Console.WriteLine(racers[i]);
}
Indexed access to collection classes is available with ArrayList , StringCollection ,
and List < T > .
Because List < T > implements the interface IEnumerable , you can iterate through the items in the collection
using the foreach statement as well:
foreach (Racer r in racers)
{
Console.WriteLine(r);
}
How the foreach statement is resolved by the compiler to make use of the
IEnumerable and IEnumerator interfaces is explained in Chapter 6.
Instead of using the foreach statement, the List < T > class also offers a ForEach() method that is declared
with an Action < T > parameter:
public void ForEach(Action < T > action);
The implementation of ForEach() is shown next. ForEach() iterates through every item of the collection
and invokes the method that is passed as parameter for every item.
public class List < T > : IList < T >
{
private T[] items;
//...
public void ForEach(Action < T > action)
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