Span<T>.Enumerator Struct in C#

Span<T> is a new feature introduced with C# 7.2 and supported in the .NET Core 2.1. It provides a type-safe access to a contiguous area of memory. This memory can be located on the heap, stack or formed a unallocated memory. Span<T> is defined as a ref struct, which means it is limited to being allocated only on the Stack. The main reason for the ref struct design is to ensure that when using of Span<T> it causes no additional heap allocations. Span<T> improves execution speed and reducing memory allocations in existing code.

Here, Span<T> references some contiguous memory(colored blocks) that has already been allocated.

Span<T>.Enumerator struct provides an enumerator for the elements of a Span<T>. Where Span<T> provides a type and memory safe representation of a contiguous region of arbitrary memory.


public struct Span<T>.Enumerator

Here the parameter is T, where T is the type of items in the Span<T>.






// C# program to demonstrate Span<T>.Enumerator Struct
using System;
using System.Threading.Tasks;
class GFG {
    // a array "arr" type of byte
    private static byte[] arr = new byte[4];
    // main method
    static void Main()
        // ramdomly fillup the array "arr"
        new Random(30).NextBytes(arr);
        // implicitly cast the array
        // "arr" to span<byte>
        Span<byte> sp = arr;
        // Task.Run() method executes
        // the clear() method
        // to clear the array for 
        // each thread operations
        Task.Run(() => clear());
        // call the function "print"
    public static void clear()
        // delay for 10ms
        // defines that one thread 
        // executes one task at one time
            Array.Clear(arr, 0, arr.Length);
    // print function
    public static void print(Span<byte> span)
        foreach(byte e in span)





  • Current: It is used to get a reference to the item at the current position of the enumerator.


  • MoveNext(): It advances the enumerator to the next item of the Span<T>.

Important Points:

  • Span<T> provides a type-safe access to a contiguous area of memory.
  • It cannot be used within asynchronous methods.
  • It does not implement the IEnumerator or IEnumerator<T> interface, because Span<T> enumerator is a ref struct.
  • It does not include a Reset method.
  • Foe use the Reset() method, it must be implemented as part of the interface.
  • It does not include additional heap allocation.
  • It cannot be used as a generic type argument.
  • Span<T> provides read-write access to the memory.
  • ReadOnlySpan<T> provides read-only access to a memory.

My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using or mail your article to See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Improved By : Akanksha_Rai

Article Tags :

Be the First to upvote.

Please write to us at to report any issue with the above content.