Span and two dimensional Arrays

Question

Is it possible to use the new System.Memory Span struct with two dimensional arrays of data?

double[,] testMulti = 
    {
        { 1, 2, 3, 4 },
        { 5         


        

Answer 1

You can create a Span with unmanaged memory. This will allow you to Slice and Dice indiscriminately.

unsafe
{
    Span something = new Span(pointerToarray, someLength); 
}

Full Demo

unsafe public static void Main(string[] args)
{
   double[,] doubles =  {
         { 1, 2, 3, 4 },
         { 5, 6, 7, 8 },
         { 9, 9.5f, 10, 11 },
         { 12, 13, 14.3f, 15 }
      };

   var length = doubles.GetLength(0) * doubles.GetLength(1);

   fixed (double* p = doubles)
   {
      var span = new Span(p, length);
      var slice = span.Slice(6, 5);

      foreach (var item in slice)
         Console.WriteLine(item);
   }
}

Output

7
8
9
9.5
10

Other options would be to reallocate to a single dimension array, cop the penalty and do not Pass-Go

• BlockCopy
• or p/invoke memcpy directly and use unsafe and pointers
• Cast eg multiDimensionalArrayData.Cast().ToArray()

The first 2 will be more performant for large arrays.