PHP | DirectoryIterator key() Function

The DirectoryIterator::key() function is an inbuilt function in PHP which is used to return the key for the current DirectoryIterator item.

Syntax:

string DirectoryIterator::key( void )

Parameters: This function does not accept any parameters.

Return Value: This function returns the key for the current DirectoryIterator item.

Below programs illustrate the DirectoryIterator::key() function in PHP:

Program 1:

<?php

// Create a directory Iterator
$directory = new DirectoryIterator(dirname(__FILE__));

// Loop runs for each element of directory
foreach($directory as $dir) {

    // Display the key and filename
    echo $dir->key() . " => " .
    $dir->getFilename() . "<br>";
}

?>

Output:

0 => .
1 => ..
2 => applications.html
3 => bitnami.css
4 => dashboard
5 => favicon.ico
6 => geeks.PNG
7 => gfg.php
8 => img
9 => index.php
10 => Sublime Text Build 3211 x64 Setup.exe
11 => webalizer
12 => xampp

Program 2:

<?php

// Create a directory Iterator
$directory = new DirectoryIterator(dirname(__FILE__));

// Loop runs while directory is valid
while ($directory->valid()) {

    // Check for directory element
    if($directory->isDir()) {

        // Display the key and filename
        echo $directory->key() . " => " .
        $directory->getFilename() . "<br>";
    }

    // Move to the next element
    $directory->next();
}

?>

Output:

0 => .
1 => ..
4 => dashboard
8 => img
11 => webalizer
12 => xampp

Note: The output of this function depends on the content of server folder.

Reference: https://www.php.net/manual/en/directoryiterator.key.php