Iterator::valid

(PHP 5 >= 5.0.0)

Iterator::valid — 检查当前位置是否有效

说明

abstract public boolean Iterator::valid ( void )

此方法在 Iterator::rewind() 和 Iterator::next() 方法之后被调用以此用来检查当前位置是否有效。

参数

此函数没有参数。

返回值

返回将被转换为布尔型。成功时返回 TRUE，或者在失败时返回 FALSE.

PHP手册 - N: 检查当前位置是否有效

用户评论:

hyponiq at gmail dot com (27-Sep-2011 12:12)

Take consideration when utilizing this method and using the returned value of isset([value]). The value of isset([value]) will be false for null values. I ran into this problem when checking isset([value]) against array elements whose value was null. Example: <?php $array = array(null, 1, 2, 3); $isSet = isset($array[0]); var_dump($isSet); // output: boolean(false) class AClass { public $array = (null, 1, 2, 3); function valid() { return isset($this->array[0]); } } $class = new AClass; var_dump($class->valid()); // output: boolean(false) ?>

seva dot lapsha at gmail dot com (02-Aug-2009 02:19)

If Iterator::valid() returns false, the foreach() loop will be terminated.