Double not (!!) operator in PHP

Question

What does the double not operator do in PHP?

For example:

return !! $row;

What would the code above do?

Answer 1

"not not" is a convenient way in many languages for understanding what truth value the language assigns to the result of any expression. For example, in Python:

>>> not not []
False
>>> not not [False]
True

It can be convenient in places where you want to reduce a complex value down to something like "is there a value at all?".