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Source Code

The MIInterfaceHierarchy project is located under the Chapter 9 subdirectory.

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, which 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 con-

struct. To illustrate, begin by creating a new Console Application project named CustomEnumerator.

Next, add the Car.cs and Radio.cs files defined in the SimpleException example of Chapter 7 (via

the Project ➤ Add Existing Item menu option) and update the current class definition with two

new properties (named PetName and Speed) that wrap the existing currSpeed and petName member

variables:

public class Car

{

private int currSpeed;

private string petName;

public int Speed

{

get { return currSpeed; }

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set { currSpeed = value; }

}

public string PetName

{

get { return petName; }

set { petName = value; }

}

...

}