why does in_array(0,*) always return 1

Question

why would in_array(0, array("pop")) return 1?

see docs clearly 0 is not a value in the array and this should return 0 or FALSE.

Answer 1

in_array($needle, $haystack, $strict = FALSE) searches haystack for needle using loose comparison unless strict is set. When you don't provide third "strict" argument the values will be compared according to loose comparsion rules in php. Go to http://php.net/manual/en/types.comparisons.php . You'll see this loose comparison behavior documented.

0 == "pop" is a loose comparison returning TRUE

0 === "pop" is a strict comparison returning FALSE