Array.GetEnumerator Method

July 28, 2014

Returns an IEnumerator for the Array.

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

public IEnumerator GetEnumerator()

Return Value

Type: System.Collections.IEnumerator
An IEnumerator for the Array.

Implements

IEnumerable.GetEnumerator()

[Visual Basic, C#]

The foreach statement of the C# language (for each in C++, For Each in Visual Basic) hides the complexity of the enumerators. Therefore, using foreach is recommended, instead of directly manipulating the enumerator.

Enumerators can be used to read the data in the collection, but they cannot be used to modify the underlying collection.

Initially, the enumerator is positioned before the first element in the collection. Reset also brings the enumerator back to this position. At this position, Current is undefined. Therefore, you must call MoveNext to advance the enumerator to the first element of the collection before reading the value of Current.

Current returns the same object until either MoveNext or Reset is called. MoveNext sets Current to the next element.

If MoveNext passes the end of the collection, the enumerator is positioned after the last element in the collection and MoveNext returns false. When the enumerator is at this position, subsequent calls to MoveNext also return false. If the last call to MoveNext returned false, Current is undefined. To set Current to the first element of the collection again, you can call Reset followed by MoveNext.

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 its behavior is undefined.

The enumerator does not have exclusive access to the collection; therefore, enumerating through a collection is intrinsically not a thread safe procedure. To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.

This method is an O(1) operation.

The following code example shows how to use GetEnumerator to list the elements of an array.


using System;

public class Example
{

   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {

      // Creates and initializes a new Array.
      String[] myArr = new String[10];
      myArr[0] = "The";
      myArr[1] = "quick";
      myArr[2] = "brown";
      myArr[3] = "fox";
      myArr[4] = "jumped";
      myArr[5] = "over";
      myArr[6] = "the";
      myArr[7] = "lazy";
      myArr[8] = "dog";

      // Displays the values of the Array.
      int i = 0;
      System.Collections.IEnumerator myEnumerator = myArr.GetEnumerator();
      outputBlock.Text += "The Array contains the following values:" + "\n";
      while ((myEnumerator.MoveNext()) && (myEnumerator.Current != null))
         outputBlock.Text += String.Format("[{0}] {1}", i++, myEnumerator.Current) + "\n";

   }

}


/* 
This code produces the following output.

The Array contains the following values:
[0] The
[1] quick
[2] brown
[3] fox
[4] jumped
[5] over
[6] the
[7] lazy
[8] dog

*/



Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

Show:
© 2014 Microsoft