Can I create my own error logs for debugging PHP scripts?

   error_reporting(0); 
   $old_error_handler = set_error_handler("userErrorHandler");
 
   function userErrorHandler ($errno, $errmsg, $filename, $linenum,  $vars) 
   {
     $time=date("d M Y H:i:s"); 
     // Get the error type from the error number 
     $errortype = array (1    => "Error",
                         2    => "Warning",
                         4    => "Parsing Error",
                         8    => "Notice",
                         16   => "Core Error",
                         32   => "Core Warning",
                         64   => "Compile Error",
                         128  => "Compile Warning",
                         256  => "User Error",
                         512  => "User Warning",
                         1024 => "User Notice");
      $errlevel=$errortype[$errno];
 
      //Write error to log file (CSV format) 
      $errfile=fopen("errors.csv","a"); 
      fputs($errfile,"\"$time\",\"$filename: 
      $linenum\",\"($errlevel) $errmsg\"\r\n"); 
      fclose($errfile);
 
      if($errno!=2 && $errno!=8) {
         //Terminate script if fatal error
         die("A fatal error has occurred. Script execution has been aborted");
      } 
   }