in_array()函数第三个参数的问题

class Included{}class test{    public $arr = array();    function a(Included $include){        if (in_array($include, $this->arr, true)){        	  return;        }        $this->arr[] = $include;    }}$test = new test();$test->a(new Included());$test->a(new Included());$test->a(new Included());print_r($test->arr);   //   输出Array ( [0] => Included Object ( ) [1] => Included Object ( ) [2] => Included Object ( ) )

<?php$a = 123;$arr = array('123','456');var_dump(in_array($a, $arr)); // truevar_dump(in_array($a, $arr, true)); // false?>