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：
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<?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>'; $mem2 = memory_get_peak_usage(); printf('<pre>Max memory for '.$func.'() : %0.2f kbytes Running time for '.$func.'() : %0.f s</pre>', ($mem2-$mem1)/1024.0, $time); return $list;}profile('rec_list_files', "D:\www\server");?> |
二、递归的深度优先的算法（用了一个栈来实现）
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<?phpdefine('DS', DIRECTORY_SEPARATOR);function deep_first_list_files($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 $list;}profile('deep_first_list_files', "D:\www\server");?> |
三、非递归的广度优先算法（用了一个队列来实现）
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<?phpdefine('DS', DIRECTORY_SEPARATOR);function breadth_first_files($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");?> |
希望本文所述对大家的php程序设计有所帮助。
