iterator_apply

(PHP 5 >= 5.1.0)

iterator_applyCall a function for every element in an iterator

Description

int iterator_apply ( Traversable $iterator , callable $function [, array $args ] )

Calls a function for every element in an iterator.

Parameters

iterator

The class to iterate over.

function

The callback function to call on every element.

Note: The function must return TRUE in order to continue iterating over the iterator.

args

Arguments to pass to the callback function.

Return Values

Returns the iteration count.

Examples

Example #1 iterator_apply() example

<?php
function print_caps(Iterator $iterator) {
    echo 
strtoupper($iterator->current()) . "\n";
    return 
TRUE;
}

$it = new ArrayIterator(array("Apples""Bananas""Cherries"));
iterator_apply($it"print_caps", array($it));
?>

The above example will output:

APPLES
BANANAS
CHERRIES

See Also

  • array_walk() - Apply a user function to every member of an array

Коментарии

$args is an array and each of its elements are passed to the callback as separate arguments.

so this is the right way to get args:

<?php
$ai 
= new ArrayIterator(range(02));

iterator_apply($ai, function() {
   
var_dump(func_get_args());     // use this func
   
return true;
}, array(
12));
?>

output: 

array(2) {
  [0] =>
  int(1)
  [1] =>
  int(2)
}
array(2) {
  [0] =>
  int(1)
  [1] =>
  int(2)
}
array(2) {
  [0] =>
  int(1)
  [1] =>
  int(2)
}

--------------------------------------------------
or list each args:

<?php
$ai 
= new ArrayIterator(range(02));

iterator_apply($ai, function($arg1$arg2$arg3) {
   
var_dump([$arg1$arg2$arg3]);
    return 
true;
}, array(
12));
?>

same output.
2017-11-22 08:47:21
http://php5.kiev.ua/manual/ru/function.iterator-apply.html
Be aware of the proper methods to iterate the specific Iterator you are consuming, as the implementation of the method could vary its behaviour.

For example, unlike the ArrayIterator, you can't iterate on a SplDoubleLinkedList with current() without using next() on every iteration (and then, only would iterate if you return true at the end of the callable. It is far easier then with LinkedLists use a while($it->valid()) { $it->current(); $it->next(); }

Let's see:

<?php

$ll 
= new \SplDoublyLinkedList();

$ll->push('ze');
$ll->push('ome');
$ll->push('yei');
$ll->push('nahui');

$ll->rewind();

$iterations_done iterator_apply($ll, function(Iterator $it) {

    echo 
implode("\t=>", [
       
$it->key(),
       
$it->current(),
       
ucfirst($it->current())
    ]),
"\n";
   
    return 
true;

}, array(
$ll));

echo 
"Did iterate {$iterations_done} times \n";

$ll->rewind();

$iterations_done iterator_apply($ll, function(Iterator $it) {

    echo 
implode("\t=>", [
       
$it->key(),
       
$it->current(),
       
ucfirst($it->current())
    ]),
"\n";
   
   
$it->next();
   
    return 
true;

}, array(
$ll));

echo 
"Did iterate {$iterations_done} times \n";

$ll->setIteratorMode(SplDoublyLinkedList::IT_MODE_FIFO SplDoublyLinkedList::IT_MODE_DELETE);

var_dump($ll->count());

foreach(
$ll as $key => $val) {
    echo 
"{$key}\t",ucfirst($val),"\n";
}

var_dump($ll->count());
?>

Output:

0    =>ze    =>Ze
0    =>ze    =>Ze
0    =>ze    =>Ze
0    =>ze    =>Ze
Did iterate 4 times 
0    =>ze    =>Ze
1    =>ome    =>Ome
2    =>yei    =>Yei
3    =>nahui    =>Nahui
Did iterate 4 times 
int(4)
0    Ze
0    Ome
0    Yei
0    Nahui
int(0)
2018-08-19 22:35:16
http://php5.kiev.ua/manual/ru/function.iterator-apply.html
Each of the arguments required by the function, must be in the array supplied in the third argument to iterator_apply. You can use references too. Example:

<?php

function translate_to(string $target_languageIterator $words, array $dictionaries) {
   
   
$language ucfirst($target_language);
   
$dictionary $dictionaries[$target_language] ?? 'not found';
   
    if (
$dictionary === 'not found') {
        echo 
"Not found dictionary for {$language}\n";
        return;
    }
   
    echo 
"English words translated to {$language}\n";
   
   
$not_found = [];
   
   
iterator_apply($words, function($words$dictionary, &$not_found){
   
       
$english_word $words->current();
   
       
$translated_word $dictionary[$english_word] ?? '';
   
        if (
$translated_word !== '') {
            echo 
"{$english_word} translates to {$translated_word}\n";
        } else {
           
$not_found[] = $english_word;
        }

        return 
true;
   
    }, array(
$words$dictionary, &$not_found));
   
    echo 
"\nNot found words:\n" implode("\n"$not_found) . "\n";
}

$dictionaries = [
   
'nahuatl' => [
       
'one' => 'Ze',
       
'two' => 'Ome',
       
'three' => 'Yei',
       
'four' => 'Nahui',
    ],
];

$iterator = new \ArrayIterator(array('one''two''three''four''gasoil'));

translate_to('nahuatl'$iterator$dictionaries);
?>

English words translated to Nahuatl
one translates to Ze
two translates to Ome
three translates to Yei
four translates to Nahui

Not found words:
gasoil
2018-08-19 23:43:23
http://php5.kiev.ua/manual/ru/function.iterator-apply.html

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