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?

blind guess: BitConverter & ByteArray doesn't work well together? — Thomas Ayoub
– Thomas Ayoub, Commented Dec 14, 2015 at 13:04
guid.ToByteArray() Returns a 16-element byte array that contains the value of this instance. — Amit Kumar Ghosh
– Amit Kumar Ghosh, Commented Dec 14, 2015 at 13:05
"half of them are in the wrong order" - wrong depends on what you think is the right order. The bytes are printed in a different order - that would be more true. And it would directly lead to the question, what might be the reason? Good terminology is half way to the solution. — JensG
– JensG, Commented Dec 14, 2015 at 13:05

BlueTrin · Accepted Answer · 2015-12-14 13:04:38Z

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)

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