There are several options that can be set on parsers, called features. The exact list of features can be found via Querying Functionality or in the API reference for raptor_set_feature(). (This should be properly called raptor_parser_set_feature() as it only applies to raptor_parser objects).

Features are integer enumerations of the raptor_feature enum and have values that are either integers (often acting as booleans) or strings. The two functions that set features are:

  /* Set an integer (or boolean) valued feature */
  raptor_set_feature(rdf_parser, feature, 1);

  /* Set a string valued feature */
  raptor_set_feature_string(rdf_parser, feature, "abc");

There are also two corresponding functions for reading the values of parser features: raptor_get_feature() and raptor_get_feature_string() taken the feature enumeration parameter and returning the integer or string value correspondingly.