- Documentation
- Reference manual
- Foreign Language Interface
- The Foreign Include File
- Argument Passing and Control
 - Atoms and functors
 - Analysing Terms via the Foreign Interface
 - Constructing Terms
 - Unifying data
 - Convenient functions to generate Prolog exceptions
 - BLOBS: Using atoms to store arbitrary binary data
 - Exchanging GMP numbers
 - Calling Prolog from C
 - Discarding Data
 - Foreign Code and Modules
 - Prolog exceptions in foreign code
 - Catching Signals (Software Interrupts)
 - Miscellaneous
 - Errors and warnings
 - Environment Control from Foreign Code
 - Querying Prolog
 - Registering Foreign Predicates
 - Foreign Code Hooks
 - Storing foreign data
 - Embedding SWI-Prolog in other applications
 
 
 - The Foreign Include File
 
 - Foreign Language Interface
 - Packages
 
 - Reference manual
 
11.4.15 Errors and warnings
PL_warning() 
prints a standard Prolog warning message to the standard error (user_error) 
stream. Please note that new code should consider using PL_raise_exception() 
to raise a Prolog exception. See also section 
4.11.
- int PL_warning(format, a1, ...)
 - Print an error message starting with `
[WARNING:', followed by the output from format, followed by a `]' and a newline. Then start the tracer. format and the arguments are the same as for printf(2). Always returnsFALSE.