php遍历树的常用方法汇总_PHP教程

php遍历树的常用方法汇总

2020-09-29 15:56疯狂的流浪 PHP教程

这篇文章主要介绍了php遍历树的常用方法,实例分析了php常用的三种遍历树的技巧,需要的朋友可以参考下

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");

									?>