php遍历树的常用方法汇总

本文实例讲述了php遍历树的常用方法。分享给大家供大家参考。具体如下：

一、递归的深度优先的算法：

    <?php
    define('DS', DIRECTORY_SEPARATOR);
    function rec_list_files($from = '.')
    {
      if(!is_dir($from)) {
        return array();
      }
      $files = array();
      if($dh = opendir($from))
      {
        while(false !== ($file = readdir($dh))) {
          if($file == '.' || $file == '..') {
            continue;
          }
          $path = $from . DS . $file;

          if (is_file($path)) {
            $files[] = $path;
          }
          $files = array_merge($files, rec_list_files($path));
        }
        closedir($dh);
      }
      return $files;
    }
    function profile($func, $trydir)
    {
      $mem1 = memory_get_usage();
      echo '<pre>----------------------- Test run for '.$func.'() ';
      flush();
      $time_start = microtime(true);
      $list = $func($trydir);
      //print_r($list);
      $time = microtime(true) - $time_start;
      echo 'Finished : '.count($list).' files</pre>';
      $mem2 = memory_get_peak_usage();
      printf('<pre>Max memory for '.$func.'() : %0.2f kbytes Running time for '.$func.'() : %0.f s</pre>',
      ($mem2-$mem1)/1024.0, $time);
      return $list;
    }
    profile('rec_list_files', "D:\www\server");
    ?>

二、递归的深度优先的算法（用了一个栈来实现）

    <?php
    define('DS', DIRECTORY_SEPARATOR);
    function deep_first_list_files($from = '.')
    {
      if(!is_dir($from)) {
        return false;
      }
      $files = array();
      $dirs = array($from);
      while(NULL !== ($dir = array_pop($dirs))) {
        if( $dh = opendir($dir)) {
          while( false !== ($file = readdir($dh))) {
            if($file == '.' || $file == '..') {
              continue;
            }
            $path = $dir . DS . $file;
            if(is_dir($path)) {
              $dirs[] = $path;
            } else {
              $files[] = $path;
            }
          }
          closedir($dh);
        }
      }
      return $files;
    }
    function profile($func, $trydir)
    {
      $mem1 = memory_get_usage();
      echo '<pre>----------------------- Test run for '.$func.'() ';
      flush();
      $time_start = microtime(true);
      $list = $func($trydir);
      //print_r($list);
      $time = microtime(true) - $time_start;
      echo 'Finished : '.count($list).' files</pre>';
      $mem2 = memory_get_peak_usage();
      printf('<pre>Max memory for '.$func.'() : %0.2f kbytes Running time for '.$func.'() : %0.f s</pre>',
      ($mem2-$mem1)/1024.0, $time);
      return $list;
    }
    profile('deep_first_list_files', "D:\www\server");
    ?>

三、非递归的广度优先算法（用了一个队列来实现）

    <?php
    define('DS', DIRECTORY_SEPARATOR);
    function breadth_first_files($from = '.') {
      $queue = array(rtrim($from, DS).DS);// normalize all paths
      $files = array();
      while($base = array_shift($queue )) {
        if (($handle = opendir($base))) {
          while (($child = readdir($handle)) !== false) {
            if( $child == '.' || $child == '..') {
              continue;
            }
            if (is_dir($base.$child)) {
              $combined_path = $base.$child.DS;
              array_push($queue, $combined_path);
            } else {
              $files[] = $base.$child;
            }
          }
          closedir($handle);
        } // else unable to open directory => NEXT CHILD
      }
      return $files; // end of tree, file not found
    }
    function profile($func, $trydir)
    {
      $mem1 = memory_get_usage();
      echo '<pre>----------------------- Test run for '.$func.'() ';
      flush();
      $time_start = microtime(true);
      $list = $func($trydir);
      //print_r($list);
      $time = microtime(true) - $time_start;
      echo 'Finished : '.count($list).' files</pre>';
      $mem2 = memory_get_peak_usage();
      printf('<pre>Max memory for '.$func.'() : %0.2f kbytes Running time for '.$func.'() : %0.f s</pre>',
      ($mem2-$mem1)/1024.0, $time);
      return $list;
    }
    profile('breadth_first_files', "D:\www\server");
    ?>

希望本文所述对大家的php程序设计有所帮助。