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

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。