(PHP 5 >= 5.1.3)
RecursiveIteratorIterator::__construct — Construct a RecursiveIteratorIterator
$iterator
   [, int $mode = RecursiveIteratorIterator::LEAVES_ONLY
   [, int $flags = 0
  ]] )Creates a RecursiveIteratorIterator from a RecursiveIterator.
iteratorThe iterator being constructed from. Either a RecursiveIterator or IteratorAggregate.
modeOptional mode. Possible values are
RecursiveIteratorIterator::LEAVES_ONLY
         - The default. Lists only leaves in iteration.
        RecursiveIteratorIterator::SELF_FIRST
         - Lists leaves and parents in iteration with parents coming first.
        RecursiveIteratorIterator::CHILD_FIRST
         - Lists leaves and parents in iteration with leaves coming first.
        flags
       Optional flag. Possible values are RecursiveIteratorIterator::CATCH_GET_CHILD
       which will then ignore exceptions thrown in calls to RecursiveIteratorIterator::getChildren().
      
No value is returned.
Example #1 Iterating a RecursiveIteratorIterator
<?php
$array = array(
    array(
        array(
            array(
                'leaf-0-0-0-0',
                'leaf-0-0-0-1'
            ),
            'leaf-0-0-0'
        ),
        array(
            array(
                'leaf-0-1-0-0',
                'leaf-0-1-0-1'
            ),
            'leaf-0-1-0'
        ),
        'leaf-0-0'
    )
);
$iterator = new RecursiveIteratorIterator(
    new RecursiveArrayIterator($array),
    $mode
);
foreach ($iterator as $key => $leaf) {
    echo "$key => $leaf", PHP_EOL;
}
?>
Output with $mode = RecursiveIteratorIterator::LEAVES_ONLY
0 => leaf-0-0-0-0 1 => leaf-0-0-0-1 0 => leaf-0-0-0 0 => leaf-0-1-0-0 1 => leaf-0-1-0-1 0 => leaf-0-1-0 0 => leaf-0-0
Output with $mode = RecursiveIteratorIterator::SELF_FIRST
0 => Array 0 => Array 0 => Array 0 => leaf-0-0-0-0 1 => leaf-0-0-0-1 1 => leaf-0-0-0 1 => Array 0 => Array 0 => leaf-0-1-0-0 1 => leaf-0-1-0-1 1 => leaf-0-1-0 2 => leaf-0-0
Output with $mode = RecursiveIteratorIterator::CHILD_FIRST
0 => leaf-0-0-0-0 1 => leaf-0-0-0-1 0 => Array 1 => leaf-0-0-0 0 => Array 0 => leaf-0-1-0-0 1 => leaf-0-1-0-1 0 => Array 1 => leaf-0-1-0 1 => Array 2 => leaf-0-0 0 => Array