Pro C# 2010 and the .NET 4 Platform, Fifth Edition

9.11. Building Enumerable Types (IEnumerable and IEnumerator)

To begin examining the process of implementing existing .NET interfaces, let's first look at the role of IEnumerable and IEnumerator. Recall that C# supports a keyword named foreach that allows you to iterate over the contents of any array type:

// Iterate over an array of items.
int[] myArrayOfInts = {10, 20, 30, 40};

foreach(int i in myArrayOfInts)
{
  Console.WriteLine(i);
}

While it may seem that only array types can make use of this construct, the truth of the matter is any type supporting a method named GetEnumerator() can be evaluated by the foreach construct. To illustrate, begin by creating a new Console Application project named CustomEnumerator. Next, add the Car.cs and ...