filter_id
  (PHP 5 >= 5.2.0, PECL filter:0.11.0)
filter_id — Returns the filter ID belonging to a named filter
  
 
  Description
  
   int filter_id
    ( string $filtername
   )
  
 
  Parameters
  
   
    - 
     filtername
     
- 
      
       Name of a filter to get.
       
 
 
  Return Values
  
   ID of a filter on success or NULL if filter doesn't exist.