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

It's the same (or almost the same - there might be some corner case) as casting to bool. If $row would cast to true, then !! $row is also true.

But if you want to achieve (bool) $row, you should probably use just that - and not some "interesting" expressions ;)