php foreach loop a folder get files in its' subfolder

Question

I have some error_log.txt files, create in /var/www/html/log/'.date(Ymd).'/error_log.txt, The folder table like this.

-log-
    |--20120825 -- error_log.txt
    |--20120826 -- 
    |--20120827 -- error_log.txt
    |--20120828 -- error_log.txt

How to make a foreach loop in folder which name as log, then get all the subfolder name and make a judgment if there has error_log.txt in this subfolder?

As the folder table show, 20120826 have no error_log.txt in it, so do not print the folder name.

Finally I need get the folder name: 20120825, 20120827, 20120828

$folder = dirname(__FILE__) . '/../log/';
foreach(glob($folder) as $subfolder){
  if(file_exists($subfolder.'/error_log.txt')){
    echo  $subfolder.'<br />'; //I get nothing.
  }
}

Answer 1

$folder = dirname(__FILE__) . '/../log/';
foreach (new RecursiveIteratorIterator(new RecursiveDirectoryIterator($folder)) as $entry) {
  if ($entry->isFile()) {
    echo $entry, '<br />';
  }
}

Used in this way, you'll only get actual files. And if you don't like the iterator style, use:

$folder = dirname(__FILE__) . '/log/*';
foreach(glob($folder) as $subfolder){
  $path = $subfolder . '/error_log.txt';
  if (file_exists($path)) {
    echo basename($subfolder), '<br />';
  }
}