Question

Which is the correct format for negating instanceof?

if ( ! $a instanceof stdClass)

or

if ( ! ($a instanceof stdClass) ) 

I’ve convinced myself the latter is correct way, probably after reading a blog article several years ago, but after some command-line tests, they both seem equivalent. Are they?

Answer 1

Let’s read the docs:

The following table lists the operators in order of precedence, with the highest-precedence ones at the top.[…]

Associativity      Operators       Additional Information
================== =============== ======================
non-associative    instanceof      types
right              !               logical

So instanceof has higher priority, thus both statements are equivalent. Parenthesis are probably used to make it obvious so you don’t need to look it up in the documentation.