IEnumerator in Dotnet

 IEnumerator in Dotnet

`IEnumerator` is an interface provided by the .NET framework, primarily used for iterating through collections of objects. It defines methods for iterating over a collection in a forward-only, read-only manner. The `IEnumerator` interface is part of the System.Collections namespace.

Here's the basic structure of the `IEnumerator` interface:

csharp

public interface IEnumerator

{

    bool MoveNext();

    void Reset();

    object Current { get; }

}

- `MoveNext()`: Advances the enumerator to the next element of the collection. It returns `true` if there are more elements to iterate; otherwise, it returns `false`.

- `Reset()`: Resets the enumerator to its initial position before the first element in the collection.

- `Current`: Gets the current element in the collection. This is an object because `IEnumerator` is not type-specific.

Implementing IEnumerator:

You can implement the `IEnumerator` interface in your custom collection classes to enable them to be iterated using `foreach` loops.

Here's an example of a custom collection that implements the `IEnumerator` interface:

```csharp

public class CustomCollection : IEnumerable, IEnumerator

{

    private object[] _items;

    private int _currentIndex = -1;

    public CustomCollection(object[] items)

    {

        _items = items;

    }

    public IEnumerator GetEnumerator()

    {

        return this;

    }

    public bool MoveNext()

    {

        _currentIndex++;

        return _currentIndex < _items.Length;

    }

    public void Reset()

    {

        _currentIndex = -1;

    }

    public object Current

    {

        get

        {

            try

            {

                return _items[_currentIndex];

            }

            catch (IndexOutOfRangeException)

            {

                throw new InvalidOperationException();

            }

        }

    }

}

In this example, `CustomCollection` implements both `IEnumerable` and `IEnumerator`. The `GetEnumerator` method returns the current object as the enumerator, and `MoveNext`, `Reset`, and `Current` methods are implemented to fulfill the `IEnumerator` contract.

Usage of `IEnumerator` allows you to create custom collections that can be iterated in a `foreach` loop, providing a consistent and familiar way to work with your data structures. When implementing `IEnumerator`, be mindful of the iteration state, especially after reaching the end of the collection.