三种遍历树的方法

 1 define('DS', DIRECTORY_SEPARATOR);
 2  function rec_list_files($from = '.') {
 3     if(!is_dir($from)) {
 4         return array();
 5     }
 6     $files = array();
 7     if($dh = opendir($from)) {
 8         while(false !== ($file = readdir($dh))) {
 9             if($file == '.' || $file == '..') {
10                 continue;
11             }
12             $path = $from . DS . $file;
13             if (is_file($path)) {
14                 $files[] = $path;
15             }
16             $files = array_merge($files, rec_list_files($path));
17         }
18         closedir($dh);
19     }
20     return $files;
21 }
22 
23 function deep_first_list_files($from = '.') {
24     if(!is_dir($from)) {
25         return false;
26     }
27     $files = array();
28     $dirs = array($from);
29     while(NULL !== ($dir = array_pop($dirs))) {
30         if( $dh = opendir($dir)) {
31             while( false !== ($file = readdir($dh))) {
32                 if($file == '.' || $file == '..') {
33                     continue;
34                 }
35                 $path = $dir . DS . $file;
36                 if(is_dir($path)) {
37                     $dirs[] = $path;
38                 } else {
39                     $files[] = $path;
40                 }
41             }
42             closedir($dh);
43         }
44     }
45     return $files;
46 }
47 
48 function breadth_first_files($from = '.') {
49     $queue = array(rtrim($from, DS).DS);// normalize all paths
50     $files = array();
51     while($base = array_shift($queue )) {
52         if (($handle = opendir($base))) {
53             while (($child = readdir($handle)) !== false) {
54                 if( $child == '.' || $child == '..') {
55                     continue;
56                 }
57                 if (is_dir($base.$child)) {
58                     $combined_path = $base.$child.DS;
59                     array_push($queue, $combined_path);
60                 } else {
61                     $files[] = $base.$child;
62                 }
63             }
64             closedir($handle);
65         }// else unable to open directory => NEXT CHILD
66     }
67     return $files; // end of tree, file not found
68 }
69 
70 function profile($func, $trydir) {
71     $mem1 = memory_get_usage();
72     echo '<pre>----------------------- Test run for '.$func.'() ';
73     flush();
74     $time_start = microtime(true);
75     $list = $func($trydir);     //print_r($list);
76     $time = microtime(true) - $time_start;
77     echo 'Finished : '.count($list).' files</pre>';
78     $mem2 = memory_get_peak_usage();
79     printf('<pre>Max memory for '.$func.'() : %0.2f kbytes Running time for '.$func.'() : %0.f s</pre>',     ($mem2-$mem1)/1024.0, $time);
80     return $list;
81 }
82 
83 profile('rec_list_files', "D:\www\server");
84 profile('deep_first_list_files', "D:\www\server");
85 profile('breadth_first_files', "D:\www\server");
86 
87