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

$a != $b

TRUE if $a is not equal to $b after type juggling.

$a !== $b

TRUE if $a is not equal to $b, or they are not of the same type.

---

See type juggling in PHP for more info on type juggling.

---

Sources : php.net