SWI-Prolog -- API-function PL

Documentation
- Reference manual
  - Foreign Language Interface
    - The Foreign Include File
      - Errors and warnings
        
        PL_warning()
- Packages

Availability:C-language interface function

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 returns FALSE.