SWI-Prolog Reference Manual: Section 5.6.13

5.6.13 Querying Prolog

C_type 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. The options are given in table 7.

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_QUERY_ORGSYMBOLFILE Return the initial symbol file (before loading) of Prolog. By setting the symbol file to this value no name clashes can occur with previously loaded foreign files (but no symbols can be shared with earlier loaded modules as well).

PL_MAX_INTEGER Return a long, representing the maximal integer value represented by Prolog's tagged integers.

PL_MIN_INTEGER Return a long, represented the minimal integer value.

PL_QUERY_VERSION Return a long, representing the version as 10,000 × M + 100 × m + p, where Mis the major,mthe minor version number andpthe patch-level. For example, 20717means2.7.17.

Table 7 : PL_query() options

`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_QUERY_ORGSYMBOLFILE`	Return the initial symbol file (before loading) of Prolog. By setting the symbol file to this value no name clashes can occur with previously loaded foreign files (but no symbols can be shared with earlier loaded modules as well).
`PL_MAX_INTEGER`	Return a long, representing the maximal integer value represented by Prolog's tagged integers.
`PL_MIN_INTEGER`	Return a long, represented 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`.