Generic ForEach For Multidimensional Array

[Jimmy-Hu]

Background and Motivation

There is a method Array.ForEach existed public static void ForEach<T>(T[] array, Action<T> action); and its input is specified on one dimensional array case. I want to propose another version Array.ForEach implementation for multidimensional array cases (ForEach([,], ...), ForEach([,,], ...) and ForEach([,,,], ...))

Proposed API

namespace System
{
    public abstract class Array : ICollection, IEnumerable, IList, IStructuralComparable, IStructuralEquatable, ICloneable
    {
+        public static void ForEach<T>(Array array, in Action<T> action)
+            where T : unmanaged
+        {
+            if (ReferenceEquals(array, null))
+            {
+                throw new ArgumentNullException(nameof(array));
+            }
+        
+            if (ReferenceEquals(action, null))
+            {
+                throw new ArgumentNullException(nameof(action));
+            }
+        
+            foreach (T item in array)
+            {
+                action.Invoke(item);
+            }
+            return;
+        }
    }
}

Usage Examples

The usage examples which include one dimensional case, two dimensional case and three dimensional case are as below.

//    One dimensional case
Console.WriteLine("One dimensional case");
int[] test = new int[] { 1, 2, 3, 4 };
Array.ForEach<int>(test, ShowSquares);

//    two dimensional case
Console.WriteLine("Two dimensional case");
int[,] test2 = { { 0, 1 }, { 2, 3 } };
Array.ForEach<int>(test2, ShowSquares);

//    three dimensional case
Console.WriteLine("Three dimensional case");
int[,,] test3 = { { { 0, 1 }, { 2, 3 } }, { { 0, 1 }, { 2, 3 } } };
Array.ForEach<int>(test3, ShowSquares);

/// <summary>
/// Reference: https://docs.microsoft.com/en-us/dotnet/api/system.array.foreach?view=net-5.0
/// </summary>
/// <param name="val">The input value for displaying and calculating square result</param>
private static void ShowSquares(int val)
{
    Console.WriteLine("{0:d} squared = {1:d}", val, val * val);
}

The output of the above tests:

One dimensional case
1 squared = 1
2 squared = 4
3 squared = 9
4 squared = 16
Two dimensional case
0 squared = 0
1 squared = 1
2 squared = 4
3 squared = 9
Three dimensional case
0 squared = 0
1 squared = 1
2 squared = 4
3 squared = 9
0 squared = 0
1 squared = 1
2 squared = 4
3 squared = 9

Reference

• ForEach Methods Implementation for Multidimensional Array in C#

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[Jimmy-Hu]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

I think that the area is area-System.Runtime.

[huoyaoyuan]

This implementation boxes and unboxes via non-generic IEnumerable. It should be not OK for new BCL api.

[huoyaoyuan]

Related: #49269

If MD array implements generic IEnuemrable<T> in some way, this API will be more actionable.