Convert byte array to collection of enums in C#

Question

I have a byte array that recevies enums in little endianess byte order from a function GetData() and I want to convert the array into a collection of enums. How would I copy and cast the bytes in LE order to the enum values in C#? I have a C++ background and not too familiar with the language. This is a sample code snippet:

public enum BarID
{
  TAG0 = 0x0B01,
  TAG1 = 0x0B02,
}

public class TestClass
{
  List<BarID> ids;
  internal TestClass() 
  {
      ids = new List<BarID>();
      byte[] foo = GetData(); // returns  01 0b 00 00 02 0b 00 00
      // cast byte array so that ids contains the enums 'TAG0' and 'TAG1'      

  }
}

Answer 1

Though Marc's answer is both good and fast, that works only on .NET Core, or if you use additional nugets. If that could be a problem (or you target older Framework versions) you can use a solution like this:

var bytes = new byte[] { 0x01, 0x0b, 0x00, 0x00, 0x02, 0x0b, 0x00, 0x00 };

return BitConverter.IsLittleEndian
    ? ConvertLittleEndian(bytes)
    : ConvertBigEndian(bytes);

Where the conversion methods:

private static unsafe BarID[] ConvertLittleEndian(byte[] bytes)
{
    var barIds = new BarID[bytes.Length / 4];
    fixed (byte* pBytes = bytes)
    {
        BarID* asIds = (BarID*)pBytes;
        for (int i = 0; i < barIds.Length; i++)
            barIds[i] = asIds[i];
    }

    return barIds;
}

If you know that your code will be used on little endian CPUs (eg. it is meant to be a Windows app), then you don't even need the big endian version:

private static BarID[] ConvertBigEndian(byte[] bytes)
{
    var barIds = new BarID[bytes.Length / 4];
    for (int i = 0; i < barIds.Length; i++)
    {
        int offset = i * 4;
        barIds[i] = (BarID)((bytes[offset] << 3) | (bytes[offset + 1] << 2)
            | (bytes[offset + 2] << 1) | bytes[offset + 3]);
    }

    return barIds;
}