We need to get a list of specific files from a directory.

Say we need to find all *.php files in our c:\inetpub\wwwroot folder. There are a couple of options to do it in PHP: opendir(), glob(), scandir() and RecursiveDirectoryIterator class. If we need to search through subfolders then the simplest solution in my opinion is to use the RecursiveDirectoryIterator class.

function readdirRecursiveDirectory($dir, $extension)   
 {  
   $files = array();  
   if (!file_exists($dir))  
     return $files;  
   $strRegexp = '/^.+\.'.$extension.'$/i';  //note the i here - case insensitive regexp
   $iteratorDirectory = new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator($dir));  
   $iteratorRegex = new \RegexIterator($iteratorDirectory, $strRegexp, \RecursiveRegexIterator::GET_MATCH);  
   foreach ($iteratorRegex as $filepath => $fileinfo)   
   {  
     if ( is_file($filepath) )   
     {  
       $files[] = $filepath;  
     }  
   }  
   return $files;  
 }

But there is a faster solution based on scandir() php buildin function. This recursive function is about 5% faster in my tests then the previous solution.

function readdirScandir($dir, $extension)
{ 
    $files = array();
    $root = @scandir($dir, SCANDIR_SORT_NONE);
    foreach($root as $entry)
    {
        if($entry === '.' || $entry === '..') 
            continue;

        $fullpath = $dir.'/'.$entry;
        if(is_file($fullpath)) 
        {
            if (0 === strcasecmp($extension, pathinfo($fullpath, PATHINFO_EXTENSION)))
                $files[] = $fullpath;
            continue;
        }

        foreach(readdirScandir($fullpath, $extension) as $entry)
        {
            if(0 === strcasecmp($extension, pathinfo($entry, PATHINFO_EXTENSION)))
            {
                $files[] = $entry;
            }
        }
    }
    return $files;
}

My results searching for 2173 php-files through c:\inetpub\wwwroot directory with totally ~90000 files in 10927 folders.

readdirRecursiveDirectory - 42sec
readdirScandir - 39sec