Question

I am converting a string to a guid to check if the string is a valid guid , in c# .net 4.0
The string is :

string guid = "11111111-1111-1111-1111-111111111111";

This guid should be invalid for me , even though it have as many characters as a guid have. Is there a way to check if a guid looks like a “normal” guid with different chars and numbers?

All these methods dont work because they return the guid is valid for me.

Guid.Parse

Guid.TryParse

Guid.TryParseExact

Thank you!

EDIT :

To clarify, i need to check if my guid is like these Guids : dc6a1ad8-4743-4487-a28e-54d31870dfcb

We can discard the word “invalid” and “valid” because people seem to focus a bit on that. So i need make sure a guid looks more like this : dc6a1ad8-4743-4487-a28e-54d31870dfcb instead of this : 11111111-1111-1111-1111-111111111111

Answer 1

If you just want to check whether the Guid has different characters, you can check the number of distinct bytes it contains:

int count = yourGuid.ToByteArray().Distinct().Count();

For Guid.Empty or 11111111-1111-1111-1111-111111111111, the result will be 1.
For dc6a1ad8-4743-4487-a28e-54d31870dfcb, the result is 16.

You’ll just need to decide how large the number needs to be for you to accept the Guid as “normal”.