php遍历树的常用方法汇总
作者：疯狂的流浪
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");
?>
希望本文所述对大家的php程序设计有所帮助。