What is the difference between IEnumerator and IEnumerable

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Possible Duplicate    Can anyone explain IEnumerable and IEnumerator to me        What are the differences between IEnumerator and IEnumerable

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An IEnumerator is a thing that can enumerate  it has the Current property and the MoveNext and Reset methods  which in  NET code you probably won t call explicitly  though you could    An IEnumerable is a thing that can be enumerated   which simply means that it has a GetEnumerator method that returns an IEnumerator   Which do you use   The only reason to use IEnumerator is if you have something that has a nonstandard way of enumerating  that is  of returning its various elements one-by-one   and you need to define how that works   You d create a new class implementing IEnumerator   But you d still need to return that IEnumerator in an IEnumerable class   For a look at what an enumerator  implementing IEnumerator lt T gt   looks like  see any Enumerator lt T gt  class  such as the ones contained in List lt T gt   Queue lt T gt   or Stack lt T gt    For a look at a class implementing IEnumerable  see any standard collection class

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IEnumerable and IEnumerator are both interfaces  IEnumerable has just one method called GetEnumerator  This method returns  as all methods return something including void  another type which is an interface and that interface is IEnumerator  When you implement enumerator logic in any of your collection class  you implement IEnumerable  either generic or non generic   IEnumerable has just one method whereas IEnumerator has 2 methods  MoveNext and Reset  and a property Current  For easy understanding consider IEnumerable as a box that contains IEnumerator inside it  though not through inheritance or containment   See the code for better understanding   class Test   IEnumerable  IEnumerator       IEnumerator IEnumerable GetEnumerator                 throw new NotImplementedException               public object Current               get   throw new NotImplementedException                 public bool MoveNext                 throw new NotImplementedException               public void Reset                 throw new NotImplementedException

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IEnumerable is an interface that defines one method GetEnumerator which returns an IEnumerator interface  this in turn allows readonly access to a collection  A collection that implements IEnumerable can be used with a foreach statement   Definition  IEnumerable   public IEnumerator GetEnumerator     IEnumerator  public object Current  public void Reset    public bool MoveNext      example code from codebetter com

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An Enumerator shows you the items in a list or collection  Each instance of an Enumerator is at a certain position  the 1st element  the 7th element  etc  and can give you that element  IEnumerator Current  or move to the next one  IEnumerator MoveNext    When you write a foreach loop in C   the compiler generates code that uses an Enumerator   An Enumerable is a class that can give you Enumerators   It has a method called GetEnumerator which gives you an Enumerator that looks at its items   When you write a foreach loop in C   the code that it generates calls GetEnumerator to create the Enumerator used by the loop

[c#] What is the difference between IEnumerator and IEnumerable?

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