In the code below from MSDN
How do the PeopleEnum methods ever get called?
foreach (Person p in peopleList)
Console.WriteLine(p.firstName + " " + p.lastName);
What is going on behind the scenes in the foreach?
Also, I could not find where the interface signatures were for the
IEnumerable and IEnumerator. How did they know what methods they were
required to use from the interface signature. I looked them up on
MSDN, but didn't see any references to GetEnumerator or MoveNext.
Just this type explanation:
[ComVisibleAttribute(true)]
[GuidAttribute("496B0ABF-CDEE-11d3-88E8-00902754C43A")]
public interface IEnumerator
http://msdn.microsoft.com/en-us/libr...le(VS.80).aspx
Thanks.
---
using System;
using System.Collections;
public class Person
{
public Person(string fName, string lName)
{
this.firstName = fName;
this.lastName = lName;
}
public string firstName;
public string lastName;
}
public class People : IEnumerable
{
private Person[] _people;
public People(Person[] pArray)
{
_people = new Person[pArray.Length];
for (int i = 0; i < pArray.Length; i++)
{
_people[i] = pArray[i];
}
}
public IEnumerator GetEnumerator()
{
return new PeopleEnum(_people);
}
}
public class PeopleEnum : IEnumerator
{
public Person[] _people;
// Enumerators are positioned before the first element
// until the first MoveNext() call.
int position = -1;
public PeopleEnum(Person[] list)
{
_people = list;
}
public bool MoveNext()
{
position++;
return (position < _people.Length);
}
public void Reset()
{
position = -1;
}
public object Current
{
get
{
try
{
return _people[position];
}
catch (IndexOutOfRangeException)
{
throw new InvalidOperationException();
}
}
}
}
class App
{
static void Main()
{
Person[] peopleArray = new Person[3]
{
new Person("John", "Smith"),
new Person("Jim", "Johnson"),
new Person("Sue", "Rabon"),
};
People peopleList = new People(peopleArray);
foreach (Person p in peopleList)
Console.WriteLine(p.firstName + " " + p.lastName);
}
}
/* This code produces output similar to the following:
*
* John Smith
* Jim Johnson
* Sue Rabon
*
*/
