php常用的三种遍历树的技巧

本篇文章主要介绍php常用的三种遍历树的技巧，感兴趣的朋友参考下，希望对大家有所帮助。

本文实例讲述了php遍历树的常用方法，具体如下：

一、递归的深度优先的算法：

<?phpdefine('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(&<div style="color:transparent">本文来源gaodai.ma#com搞##代!^码@网*</div><pre>搞gaodaima代码

#39;<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）

<?phpdefine('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）

<?phpdefine('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");?>

总结：以上就是本篇文的全部内容，希望能对大家的学习有所帮助。

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