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Span<T>.Enumerator Struct in C#

Last Updated : 23 Mar, 2022
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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()
        // randomly 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.
  • For 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.


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