Implementing IEnumerable and IEnumerator

Working with a foreach loop is the primary reason to implement the IEnumerable and IEnumerator interfaces. You'll want one of each of these to work with the loop.
I am going to do an example DateRange class which will implement IEnumerable and will allow us to iterate through a non-existent collection of DateTime objects.
Note: I am aware of the fact that I could achieve the same result with a for loop. I find the foreach loop more readable.
First we need to create a basic DateRange class. A range can be defined as a StartDate and an EndDate, so I'll start there.
public class DateRange { public DateRange(DateTime startDate, DateTime endDate) { StartDate = startDate; EndDate = endDate; } public DateTime StartDate { get; set; } public DateTime EndDate { get; set; } }

So this DateRange could be useful on its own, but we want to be able to iterate this collection using a foreach. So to start we need to implement the IEnumerable interface.
public class DateRange : IEnumerable { public DateRange(DateTime startDate, DateTime endDate) { StartDate = startDate; EndDate = endDate; } public DateTime StartDate { get; set; } public DateTime EndDate { get; set; } public IEnumerator GetEnumerator() { return new DateRangeEnumerator(this); } IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); } }

Notice here that we now need to get the IEnumerator object in the GetEnumerator() method. I jumped the gun a bit and I've called a class that doesn't exist yet. I'll make another class and implement the required methods for the IEnumerator interface.
public class DateRangeEnumerator : IEnumerator { private int _index = -1; private readonly DateRange _dateRange; public DateRangeEnumerator(DateRange dateRange) { _dateRange = dateRange; } public void Dispose() { } public bool MoveNext() { _index++; if (_index > (_dateRange.EndDate - _dateRange.StartDate).Days) return false; return true; } public void Reset() { _index = -1; } public DateTime Current { get { return _dateRange.StartDate.AddDays(_index); } } object IEnumerator.Current { get { return Current; } } }

These are the handful of methods we implement for the IEnumerator interface. These are all about moving to the next object and getting the current object. Resetting and Disposal of the object are less important, so make sure you read MoveNext and Current.
Keep in mind here that I could have used a collection for this, but I didn't because I don't need one. The calculation to get the items was easy enough.
var dateRange = new DateRange(DateTime.Today.AddDays(-6), DateTime.Today); foreach (DateTime date in dateRange) { Console.WriteLine(date.ToShortDateString()); }

Need More Information Then Refer this Link

http://brendan.enrick.com/post/implementing-ienumerable-and-ienumerator.aspx

4 Replies

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jnmsy14y ago
Hello Gaurav,
The following video may help you..
http://bestdotnettrainers.blogspot.in/search?updated-min=2012-01-01T00:00:00-08:00&updated-max=2013-01-01T00:00:00-08:00&max-results=11
Vulpes14y ago
Enumerable is a static class in the System.Linq namespace which includes the various extension methods used by Linq for querying collections which implement the IEnumerable interface.

IEnumerator is an interface in the System.Collections namespace which contains two methods - MoveNext and Reset - and one property - Current. All types which implement IEnumerator must, of course, provide public implementations of these members.

IEnumerator is the base interface for iterating over non-generic collections and is used by the foreach statement 'under the hood'. The corresponding base interface for iterating over generic collections is IEnumerator.
Senthilkumar14y ago
Hi Gaurav,

Please refer these urls:

http://www.itorian.com/articles/c-sharp/post/339/Difference-between-IEnumerable-and-IEnumerator---By-Shivprasad-Koirala.aspx
http://social.msdn.microsoft.com/Forums/en-US/netfxbcl/thread/6b7ca838-7afc-4223-9a73-41769c496745/
http://www.codeproject.com/Articles/4074/Using-IEnumerator-and-IEnumerable-in-the-NET-Frame
Kunal Vaishya14y ago
Implementing IEnumerable and IEnumerator

Working with a foreach loop is the primary reason to implement the IEnumerable and IEnumerator interfaces. You'll want one of each of these to work with the loop.
I am going to do an example DateRange class which will implement IEnumerable and will allow us to iterate through a non-existent collection of DateTime objects.
Note: I am aware of the fact that I could achieve the same result with a for loop. I find the foreach loop more readable.
First we need to create a basic DateRange class. A range can be defined as a StartDate and an EndDate, so I'll start there.
public class DateRange { public DateRange(DateTime startDate, DateTime endDate) { StartDate = startDate; EndDate = endDate; } public DateTime StartDate { get; set; } public DateTime EndDate { get; set; } }

So this DateRange could be useful on its own, but we want to be able to iterate this collection using a foreach. So to start we need to implement the IEnumerable interface.
public class DateRange : IEnumerable { public DateRange(DateTime startDate, DateTime endDate) { StartDate = startDate; EndDate = endDate; } public DateTime StartDate { get; set; } public DateTime EndDate { get; set; } public IEnumerator GetEnumerator() { return new DateRangeEnumerator(this); } IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); } }

Notice here that we now need to get the IEnumerator object in the GetEnumerator() method. I jumped the gun a bit and I've called a class that doesn't exist yet. I'll make another class and implement the required methods for the IEnumerator interface.
public class DateRangeEnumerator : IEnumerator { private int _index = -1; private readonly DateRange _dateRange; public DateRangeEnumerator(DateRange dateRange) { _dateRange = dateRange; } public void Dispose() { } public bool MoveNext() { _index++; if (_index > (_dateRange.EndDate - _dateRange.StartDate).Days) return false; return true; } public void Reset() { _index = -1; } public DateTime Current { get { return _dateRange.StartDate.AddDays(_index); } } object IEnumerator.Current { get { return Current; } } }

These are the handful of methods we implement for the IEnumerator interface. These are all about moving to the next object and getting the current object. Resetting and Disposal of the object are less important, so make sure you read MoveNext and Current.
Keep in mind here that I could have used a collection for this, but I didn't because I don't need one. The calculation to get the items was easy enough.
var dateRange = new DateRange(DateTime.Today.AddDays(-6), DateTime.Today); foreach (DateTime date in dateRange) { Console.WriteLine(date.ToShortDateString()); }

Need More Information Then Refer this Link

http://brendan.enrick.com/post/implementing-ienumerable-and-ienumerator.aspx