arrays - Print_r() to PHP error_log() not working. (non-printing characters) -

i have static method in helper class utility::error_log() helping gracefully debug huge objects in php. method, , it's helper-method utility::toarray() below:

static function error_log($message, $data=null, $max=2) {      if(is_array($data) || is_object($data))         $data = print_r(self::toarray($data, $max),true);     if(is_array($message) || is_object($message))         $message = print_r(self::toarray($message, $max),true);      if(!empty($data))         $data = "\n".$data;      if (!strstr($message, php_eol))         $message = str_pad(" ".$message." ", 50,'=',str_pad_both);      error_log($message.$data);  }  static function toarray($object, $max = 2, $current = 0) {     if($current > $max)         return ucfirst(gettype($object)).'( ... )';      $current++;     $return = array();     foreach((array) $object $key => $data)         if (is_object($data))             $return[$key] = self::toarray($data, $max, $current);         elseif (is_array($data))             $return[$key] = self::toarray($data, $max, $current);         else             $return[$key] = $data;      return $return; } 

now may bit at, gist is, toarray makes huge object (lots of recursion) orders of magnitude smaller, , returns properties either arrays or strings. easier work with... idea being print_r($array,true) makes array string, , log it.

this doesn't work expected, however. result is:

[05-apr-2013 05:29:00] ==================================== persisting suits & shirts =================================== array (     [ 

and nothing, when call print_r($data) , print browser, get:

array (     [brs\pagebundle\entity\pageroot_folder_name] => pages     [id] => 43     [title] => suits & shirts     [depth_title] => suits & shirts     [description] => ( ... , on ... ) 

before error_log() length limitation, mention can $data = var_export($data,true) , send result error_log() no problems:

[05-apr-2013 06:00:08] ==================================== persisting suits & shirts =================================== array (     '' . "\0" . 'brs\\pagebundle\\entity\\page' . "\0" . 'root_folder_name' => 'pages',     'id' => 43,     'title' => 'suits & shirts',     'depth_title' => 'suits & shirts',     'description' => ( ... , on ... ) 

what problem? why work var_export($data,true), , print_r($data,false), not print_r($data,true)??

the answer non-printable characters. in conversion of objects arrays, , various properties strings, these strings contain non-printing control characters never see, exist, break php's error_log().

the solution rather simple, essential:

$data= preg_replace('/[^\x0a\x20-\x7e\xc0-\xd6\xd8-\xf6\xf8-\xff]/','',$data);  // or preserve extended characters, use below expression. // mind many of these still may not display correctly in logs. $data= preg_replace('/(?!\n)[[:cntrl:]]+/','',$data); 

called before sending $message error log, removes many non-printing characters while preserving many characters other pregs found removed. in case need them:

\x0a = [newline] \x20-\x7e = [space] ! " # $ % & ' ( ) * + , - . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ? @ b c d e f g h j k l m n o p q r s t u v w x y z [ \ ] ^ _ ` b c d e f g h j k l m n o p q r s t u v w x y z { | } ~ \xc0-\xd6 = À Á Â Ã Ä Å Æ Ç È É Ê Ë Ì Í Î Ï Ð Ñ Ò Ó Ô Õ Ö \xd8-\xf6 = Ø Ù Ú Û Ü Ý Þ ß à á â ã ä å æ ç è é ê ë ì í î ï ð ñ ò ó ô õ ö \xf8-\xff = ø ù ú û ü ý þ ÿ 

in end, there additional rewriting isolate functionality use elsewhere, ultimate solution simple.

edit: upon further review, seems more related bug #64439 - "\0 causes error_log strings truncated".

for wondering, \0 (or \x00 or \x0) null character, , in particular above case, result of casting of object array, returns key value of null.classname.null.propname.