(PHP 5, PHP 7)
ArrayIterator::key — Return current array key
此函数没有参数。
The current array key.
Example #1 ArrayIterator::key() example
<?php
$array = array('key' => 'value');
$arrayobject = new ArrayObject($array);
$iterator = $arrayobject->getIterator();
echo $iterator->key(); //key
?>