The question is just playing with you with confusing spacing.
b != b is the usual != (not equals) comparison.
On the other hand:
b =! b is better written as b = !b which is parsed as:
b = (!b)
Thus it’s two operators.
- First invert
b. - Then assign it back to
b.
The assignment operator returns the assigned value. Therefore, (b =! b) evaluates to true – which is what you print out.