C# 4 and .NET 4

lists ❘ 229
Collection initializers are not refl ected within the IL code of the compiled assembly.
The compiler converts the collection initializer to invoke the Add() method for every
item from the initializer list.
adding elements
You can add elements to the list with the Add() method as shown. The generic instantiated type defi nes the
parameter type of the Add() method.
var intList = new List < int > ();
intList.Add(1);
intList.Add(2);
var stringList = new List < string > ();
stringList.Add("one");
stringList.Add("two");
The variable racers is defi ned as type List < Racer > . With the new operator, a new object of the same
type is created. Because the class List < T > was instantiated with the concrete class Racer , now only Racer
objects can be added with the Add() method. In the following sample code, fi ve Formula - 1 racers are created
and added to the collection. The fi rst three are added using the collection initializer, and the last two
are added by invoking the Add() method explicitly:
var graham = new Racer(7, "Graham", "Hill", "UK", 14);
var emerson = new Racer(13, "Emerson", "Fittipaldi", "Brazil", 14);
var mario = new Racer(16, "Mario", "Andretti", "USA", 12);
var racers = new List < Racer > (20) {graham, emerson, mario};
racers.Add(new Racer(24, "Michael", "Schumacher", "Germany", 91));
racers.Add(new Racer(27, "Mika", "Hakkinen", "Finland", 20));
code snippet ListSamples/Program.cs
With the AddRange() method of the List < T > class, you can add multiple elements to the collection at once.
The method AddRange() accepts an object of type IEnumerable < T > , so you can also pass an array
as shown:
racers.AddRange(new Racer[] {
new Racer(14, "Niki", "Lauda", "Austria", 25),
new Racer(21, "Alain", "Prost", "France", 51)});
The collection initializer can be used only during declaration of the collection. The
AddRange() method can be invoked after the collection is initialized.
If you know some elements of the collection when instantiating the list, you can also pass any object
that implements IEnumerable < T > to the constructor of the class. This is very similar to the AddRange()
method:
var racers =
new List < Racer > (new Racer[] {
new Racer(12, "Jochen", "Rindt", "Austria", 6),
new Racer(22, "Ayrton", "Senna", "Brazil", 41) });
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