in C# what does 'bool = bool != true' mean?

Question

In my hunt for some help to a problem I was having I came across this:

p.Enabled = p.Enabled != true;

What exactly does this mean? Ive never seen it before,

nb: the preceeding line was var p = this.PageRepository.GetPage(id);

Answer 1

When p.Enabled is a normal bool, as Enabled properties usually are,

p.Enabled = p.Enabled != true;

is the same as

p.Enabled = ! p.Enabled;

in other words: it flips or toggles p.Enabled.

Now when Enabled is a bool? , shorthand for Nullable<bool> , the results are different:

! ((bool?) null)           -> null
((bool?) null) != true     -> true 

So p.Enabled = p.Enabled != true will set true when the old value was false or null.

Answer 2

It's an awkwardly written bool toggle switch. Each call toggles the state from true to false. I'd have written it:

p.Enabled = !p.Enabled;

Edit - I suppose I should say, awkwardly written in my opinion only.