in_array()松比较，严格比较

$array = array(
    'egg' => true,
    'cheese' => false,
    'hair' => 765,
    'goblins' => null,
    'ogres' => 'no ogres allowed in this array'
);

var_dump(in_array('wo shi sui bian shuru de ,danshi  jieguo haishi true', $array));exit;

// Loose checking -- return values are in comments

// First three make sense, last four do not

$a = in_array(null, $array);             // true
$a = in_array(false, $array);             // true
$a = in_array(765, $array);             // true
$a = in_array(763, $array);    var_dump($a);exit;        // true
$a = in_array('egg', $array);               // true
$a = in_array('hhh', $array);               // true
$a = in_array(array(), $array);              // true

为了避免产生未知错误，建议使用in_array()的第三个参数

in_array($a,array(),true);