The CallbackFilterIterator class

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The CallbackFilterIterator class


(PHP 5 >= 5.4.0, PHP 7, PHP 8)

Class synopsis

class CallbackFilterIterator extends FilterIterator implements OuterIterator {

/* Methods */

public __construct(Iterator $iterator, callable $callback)

public accept(): bool

/* Inherited methods */

public FilterIterator::accept(): bool
public FilterIterator::current(): mixed
public FilterIterator::getInnerIterator(): Iterator
public FilterIterator::key(): mixed
public FilterIterator::next(): void
public FilterIterator::rewind(): void
public FilterIterator::valid(): bool



The callback should accept up to three arguments: the current item, the current key and the iterator, respectively.

Example #1 Available callback arguments


 * Callback for CallbackFilterIterator
 * @param $current   Current item's value
 * @param $key       Current item's key
 * @param $iterator  Iterator being filtered
 * @return boolean   TRUE to accept the current item, FALSE otherwise
function my_callback($current, $key, $iterator) {
    // Your filtering code here


Any callable may be used; such as a string containing a function name, an array for a method, or an anonymous function.

Example #2 Callback basic examples


$dir = new FilesystemIterator(__DIR__);

// Filter large files ( > 100MB)
function is_large_file($current) {
    return $current->isFile() && $current->getSize() > 104857600;
$large_files = new CallbackFilterIterator($dir, 'is_large_file');

// Filter directories
$files = new CallbackFilterIterator($dir, function ($current, $key, $iterator) {
    return $current->isDir() && ! $iterator->isDot();


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