Why are these two strings not equal?

Question

I was thinking about GUIDs recently, which led me to try this code:

Guid guid = Guid.NewGuid();
Console.WriteLine(guid.ToString()); //prints 6d1dc8c8-cd83-45b2-915f-c759134b93aa
Console.WriteLine(BitConverter.ToString(guid.ToByteArray())); //prints C8-C8-1D-6D-83-CD-B2-45-91-5F-C7-59-13-4B-93-AA
bool same=guid.ToString()==BitConverter.ToString(guid.ToByteArray()); //false
Console.WriteLine(same);

You can see that all of the bytes are there, but half of them are in the wrong order when I use BitConverter.ToString. Why is this?

Answer 1

As per the Microsoft documentation:

Note that the order of bytes in the returned byte array is different from the string representation of a Guid value. The order of the beginning four-byte group and the next two two-byte groups is reversed, whereas the order of the last two-byte group and the closing six-byte group is the same. The example provides an illustration.

using System;

public class Example
{
   public static void Main()
   {
      Guid guid = Guid.NewGuid();
      Console.WriteLine("Guid: {0}", guid);
      Byte[] bytes = guid.ToByteArray();
      foreach (var byt in bytes)
         Console.Write("{0:X2} ", byt);

      Console.WriteLine();
      Guid guid2 = new Guid(bytes);
      Console.WriteLine("Guid: {0} (Same as First Guid: {1})", guid2, guid2.Equals(guid));
   }
}
// The example displays the following output:
//    Guid: 35918bc9-196d-40ea-9779-889d79b753f0
//    C9 8B 91 35 6D 19 EA 40 97 79 88 9D 79 B7 53 F0
//    Guid: 35918bc9-196d-40ea-9779-889d79b753f0 (Same as First Guid: True)