Does PHP negation check with `!` coprrespond to `!=` or to `!==`?

Question

In PHP, is

if(!$foo)

equivalent with

if($foo != true)

or with

if($foo !== true)

Answer 1

Note that,

== OR != compares the values of variables for equality, type casting as necessary. === OR !== checks if the two variables are of the same type AND have the same value.

This answer will give you better explanation of this concept: https://stackoverflow.com/a/80649/3067928