#include <quintus/quintus.h>
     int QP_initialize(argc, argv)
     int    argc;
     char **argv;

Initializes Prolog's memory management, I/O, symbol table, etc.


number of command line arguments (or 0)
list of command line arguments (or NULL)


You can ignore QP_initialize() if you aren't redefining main().

Must be called before any other QP_ functions if you are redefining main() (in which case your top-level view of Prolog is via QP_predicate() and QP_query()).

Summary of functionality: Initializes memory, I/O; sets up command line arguments; initializes file search paths, file tables and symbol tables; do initializations and start up hooks associated with a statically linked component in qof files; do any necessary restores, and any initlization and start up hooks associated with the restored files.

QP_initialize() also sets up signal handlers so that users can interrupt the execution of a start-up goal or initialization with a ^c. If users chose the a option after a ^c (or if the builtin abort/0 is called) when initializations are run, then QP_initialize() returns. In a default system, (where main() hasnt been redefined) this means that QP_toplevel() gets called. QP_toplevel() executes the toplevel read-prove loop in a development system. In a runtime system, it results in runtime_entry(start) being called.

argc and argv are necessary for Prolog to execute the builtin unix/1 (e.g. unix(argv(_)) etc.) properly, as well as for restoring saved states.

Can be safely called any number of times.

Please note: The first call to QP_initialize() with non-null arguments will determine the command line arguments as seen by Prolog.

Return Value

Prolog was successfully initialized.


In Quintus Prolog the default implementation of main() looks like this:

     #include <quintus/quintus.h>
     main(argc, argv)
         int argc;
         char **argv;
             int status;
             status = QP_initialize(argc, argv);
             if (status == QP_SUCCESS) QP_toplevel();

The user can choose not to have the default main() and the default toplevel loop. Here is an example of how the user can call a Prolog predicate with their own main().

:- extern(hi(+atom)). hi(X) :- format('Hello world from ~a to Prolog~n',[X]).
#include <quintus/quintus.h> main(argc, argv) int argc; char **argv; { int status; QP_pred_ref pred; status = QP_initialize(argc, argv); if (status == QP_SUCCESS) { pred = QP_predicate("hi", 1, "user"); if (pred != QP_BAD_PREDREF) { status = QP_query(pred, QP_atom_from_string("C")); if (status == QP_FAILURE) { printf("hi/1 failed\n"); exit(1); } else if (status == QP_ERROR) { printf("hi/1 raised exception\n"); /* Use QP_exception_term to get the error term signaled */ exit(1); } } else { printf("hi/1 doesn't exist or "); printf("doesn't have an extern "); printf("declaration\n"); exit(1); } } else { printf("QP_initialize didn't succeed\n"); exit(1); } }

Steps to produce the executable:

  1. Compile hello.pl using qpc -c hello.pl
  2. Compile main.c using cc -c main.c
  3. Link the two using qld -Dd hello.qof main.o -o qtest
  4. Run qtest. The output should be: Hello from C to Prolog

See Also:

runtime_entry/1, unix/1, QP_predicate(), QP_query(), QP_toplevel() fli-emb