#! /usr/bin/php
<?php

//  directory_walk.php
/*  Command-line code to define and test a function to traverse a directory tree.
 */

//  Setup
//  -------------------------------------------------------------------------------------
ini_set('error_reporting', E_ALL);
ini_set('display_errors', 'On');
assert_options(ASSERT_ACTIVE, 1);
assert_options(ASSERT_BAIL, 1);
define('MAX_DEPTH', 5);

//  dir_walk()
//  -------------------------------------------------------------------------------------
/*  Walk a directory tree, printing each file or directory's name, to a depth of
 *  MAX_DEPTH. Will generate one line of output for every file and/or directory found.
 */
  function dir_walk($dir, $current_depth)
  {
    assert('is_dir($dir)');

    if ($current_depth > MAX_DEPTH || ! is_readable($dir)) return;

    $dir_handle = opendir($dir) or die("Unable to open $dir\n");
    while (false !== ($node = readdir($dir_handle)))
    {
      if ($node === '.' || $node === '..') continue;
      echo "$dir/$node\n";
      if (is_dir("$dir/$node"))
      {
        dir_walk("$dir/$node", $current_depth + 1);
      }
    }
  }

//  Test the function
//  -------------------------------------------------------------------------------------
$dir = '.';
dir_walk($dir, 0);
exit;

?>