# RecursiveIteratorIterator::__construct

(PHP 5 >= 5.1.3, PHP 7, PHP 8)

RecursiveIteratorIterator::__construct — Construct a RecursiveIteratorIterator

### 说明

public RecursiveIteratorIterator::__construct(Traversable `$iterator`, int `$mode` = `RecursiveIteratorIterator::LEAVES_ONLY`, int `$flags` = 0)

Creates a RecursiveIteratorIterator from a RecursiveIterator.

### 参数

`iterator`

  The iterator being constructed from. Either a RecursiveIterator or IteratorAggregate.

`mode`

  Optional 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().

### 示例

示例 #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

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