erties of all built-in predicates defined in C. If this function is called before PL_initialise() it returns 0.

12.4.19 Querying Prolog

long PL_query(int)

Obtain status information on the Prolog system. The actual argument type depends on the information required. int describes what information is wanted.^{199Returning pointers and integers as a long is bad style. The signature of this function should be changed.} The options are given in table 9.

PL_QUERY_ARGC	Return an integer holding the number of arguments given to Prolog from Unix.
PL_QUERY_ARGV	Return a char ** holding the argument vector given to Prolog from Unix.
PL_QUERY_SYMBOLFILE	Return a char * holding the current symbol file of the running process.
PL_MAX_INTEGER	Return a long, representing the maximal integer value represented by a Prolog integer.
PL_MIN_INTEGER	Return a long, representing the minimal integer value.
PL_QUERY_VERSION	Return a long, representing the version as 10,000 × M + 100 × m + p, where M is the major, m the minor version number and p the patch level. For example, 20717 means 2.7.17.
PL_QUERY_ENCODING	Return the default stream encoding of Prolog (of type IOENC).
PL_QUERY_USER_CPU	Get amount of user CPU time of the process in mil