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// Cast for caller.

public Person GetPerson(int pos)

{ return (Person)arPeople[pos]; }

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8849CH10.qxd  9/25/07  4:17 PM  Page 320

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// Only insert Person types.

public void AddPerson(Person p)

{ arPeople.Add(p); }

public void ClearPeople()

{ arPeople.Clear(); }

public int Count

{ get { return arPeople.Count; } }

// Foreach enumeration support.

IEnumerator IEnumerable.GetEnumerator()

{ return arPeople.GetEnumerator(); }

}

Notice that the PeopleCollection type implements the IEnumerable interface, to allow foreach-

like iteration over each contained item. Also notice that our GetPerson() and AddPerson() method

has been prototyped to only operate on Person objects (not bitmaps, strings, database connections,

or other items). With these types defined, you are now assured of type safety, given that the C# com-

piler will be able to determine any attempt to insert an incompatible type:

static void Main(string[] args)

{

Console.WriteLine("***** Custom Person Collection *****\n");

PeopleCollection myPeople = new PeopleCollection();

myPeople.AddPerson(new Person("Homer", "Simpson", 40));

myPeople.AddPerson(new Person("Marge", "Simpson", 38));

myPeople.AddPerson(new Person("Lisa", "Simpson", 9));

myPeople.AddPerson(new Person("Bart", "Simpson", 7));

myPeople.AddPerson(new Person("Maggie", "Simpson", 2));