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 => neveropen.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