array_vs_list.cs

 public class list_vs_array
 {
    int[] data;
    List<int> list;

    int calcSum;

    public list_vs_array()
    {
      data = Enumerable.Range(1, 999).ToArray();
      list = new List<int>(data);

      var length = data.Length;
      for (var i = 0; i < length; i++)
        calcSum += data[i];
    }

    [Benchmark]
    public void array_by_index()
    {
      var sum = 0;
      var length = data.Length;
      for (var i = 0; i < length; i++)
        sum += data[i];

      if (calcSum != sum)
        throw new Exception("calcSum != sum");
    }

    [Benchmark(Baseline = true)]
    public void array_by_enumerator()
    {
      var sum = 0;
      var length = data.Length;
      foreach (var item in data)
      {
        sum += item;
      }

      if (calcSum != sum)
        throw new Exception("calcSum != sum");
    }

    [Benchmark]
    public void list_by_index()
    {
      var sum = 0;
      var length = list.Count;
      for (var i = 0; i < length; i++)
        sum += list[i];

      if (calcSum != sum)
        throw new Exception("calcSum != sum");
    }

   

    [Benchmark]
    public void list_by_enumerator()
    {
      var sum = 0;
      var length = list.Count;
      foreach (var item in list)
      {
        sum += item;
      }

      if (calcSum != sum)
        throw new Exception("calcSum != sum");
    }

    [Benchmark]
    public void list_by_array_index()
    {
      var sum = 0;
      var length = list.Count;
      for (var i = 0; i < length; i++)
        sum += list._items[i];

      if (calcSum != sum)
        throw new Exception("calcSum != sum");
    }

    [Benchmark]
    public void list_by_span_index()
    {
      var sum = 0;
      var length = list.Count;
      var items = new Span<int>(list._items, 0, length);
      for (var i = 0; i < length; i++)
        sum += items[i];

      if (calcSum != sum)
        throw new Exception("calcSum != sum");
    }

    [Benchmark]
    public void list_by_span_enumerator()
    {
      var sum = 0;
      var length = list.Count;
      var items = new Span<int>(list._items, 0, length);
      foreach (var item in items)
      {
        sum += item;
      }

      if (calcSum != sum)
        throw new Exception("calcSum != sum");
    }
  }