关于 array_pad函数的疑义

关于 array_pad函数的疑问

PHP code

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<?php $city=array('li','yang','wang');
array_pad($city,5,'xie');
foreach($city as $value)
{
    print $value;
}
?>

为什么输出结果是“liyangwang”
不应该是”liyangwangxiexie“吗

------解决方案--------------------
$city = array_pad($city,5,'xie');