Search for a string in filename/foldernames using PHP

gistfile1.txt

<?php
    $search_string = ".bak";

    $count = 0;
    $output = "";
    $root      = '.';
    $iter      = new RecursiveIteratorIterator( new RecursiveDirectoryIterator( $root, RecursiveDirectoryIterator::SKIP_DOTS ), RecursiveIteratorIterator::SELF_FIRST, RecursiveIteratorIterator::CATCH_GET_CHILD );
    $i=0;
    foreach ( $iter as $path => $dir ) {
        if( stripos($dir->__toString(),$search_string) !== false){
           $output .= $dir->__toString() . "<br>";
           $count++;
        }
    }
    echo "<h3>Count: $count</h3><hr>$output";
?>