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IEnumerator.Current Property

May 11, 2014

Gets the current element in the collection.

Namespace:  System.Collections
Assembly:  mscorlib (in mscorlib.dll)

Object Current { get; }

Property Value

Type: System.Object
The current element in the collection.

ExceptionCondition
InvalidOperationException

The enumerator is positioned before the first element of the collection or after the last element.

-or-

The collection was modified after the enumerator was created.

After an enumerator is created or after the Reset method is called, the MoveNext method must be called to advance the enumerator to the first element of the collection before reading the value of the Current property; otherwise, Current is undefined.

Current also throws an exception if the last call to MoveNext returned false, which indicates the end of the collection.

Current does not move the position of the enumerator, and consecutive calls to Current return the same object until either MoveNext or Reset is called.

An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated and the next call to MoveNext or Reset throws an InvalidOperationException. If the collection is modified between MoveNext and Current, Current returns the element that it is set to, even if the enumerator is already invalidated.

The following code example demonstrates the implementation of the IEnumerator interfaces for a custom collection. In this example, Current is not explicitly called, but it is implemented to support the use of foreach (for each in Visual Basic). This code example is part of a larger example for the IEnumerator interface.


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();
         }
      }
   }
}


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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