SWI-Prolog -- API-function PL_set_query_data

Documentation
- Reference manual
  - Foreign Language Interface
    - The Foreign Include File
      - Calling Prolog from C
        
        Initiating a query from C
        
        PL_open_query()
        
        PL_next_solution()
        
        PL_cut_query()
        
        PL_close_query()
        
        PL_current_query()
        
        PL_query_engine()
        
        PL_query_arguments()
        
        PL_set_query_data()
        
        PL_query_data()
        
        PL_call_predicate()
        
        PL_call()
- Packages

Availability:C-language interface function

void* PL_set_query_data(qid_t qid, unsigned int offset, void* data)

void* PL_query_data(qid_t qid, unsigned int offset)

Associate user data with a query. offset must be smaller than PL_MAX_QUERY_DATA (currently 2). PL_set_query_data() returns the old value.