(PHP 5 >= 5.2.0)
filter_has_var — Checks if variable of specified type exists
$type
   , string $variable_name
   )
type
     
       One of INPUT_GET, INPUT_POST,
       INPUT_COOKIE, INPUT_SERVER, or
       INPUT_ENV.
      
variable_name
     Name of a variable to check.
   Returns TRUE on success or FALSE on failure.