null value in php stackoverflow

/*  == operator in PHP doesn't check for type.  
 ==, as you did, PHP treats NULL, false, 0, the 
 empty string, and empty arrays as equal.
*/

if($variable === NULL) {...}

/* check == vs ===  */

'' == NULL would return true
0 == NULL would return true
false == null would return true

where as

'' === NULL would return false
0 === NULL would return false
false === NULL would return false