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What's the difference between Guid.NewGuid() and new Guid()?
Which one is preferred?
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Guid. NewGuid() creates an empty Guid object, initializes it by calling CoCreateGuid and returns the object.
You are concerned with concurrency: fortunately, the NewGuid method is thread-safe, which means it either locks or utilizes a thread-static random number generator for its purposes.
GUIDs are most commonly written in text as a sequence of hexadecimal digits as such, 3F2504E0-4F89-11D3-9A0C-0305E82C3301. Often braces are added to enclose the above format, as such: {3F2504E0-4F89-11D3-9A0C-0305E82C3301}
To Generate a GUID in Windows 10 with PowerShell, Type or copy-paste the following command: [guid]::NewGuid() . This will produce a new GUID in the output. Alternatively, you can run the command '{'+[guid]::NewGuid(). ToString()+'}' to get a new GUID in the traditional Registry format.
new Guid() makes an "empty" all-0 guid (00000000-0000-0000-0000-000000000000 is not very useful).
Guid.NewGuid() makes an actual guid with a unique value, what you probably want.
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Guid.NewGuid() creates a new UUID using an algorithm that is designed to make collisions very, very unlikely.
new Guid() creates a UUID that is all-zeros.
Generally you would prefer the former, because that's the point of a UUID (unless you're receiving it from somewhere else of course).
There are cases where you do indeed want an all-zero UUID, but in this case Guid.Empty or default(Guid) is clearer about your intent, and there's less chance of someone reading it expecting a unique value had been created.
In all, new Guid() isn't that useful due to this lack of clarity, but it's not possible to have a value-type that doesn't have a parameterless constructor that returns an all-zeros-and-nulls value.
Edit: Actually, it is possible to have a parameterless constructor on a value type that doesn't set everything to zero and null, but you can't do it in C#, and the rules about when it will be called and when there will just be an all-zero struct created are confusing, so it's not a good idea anyway.
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