Errors and warnings

Two standard functions are available to print standard Prolog errors to the standard error stream.

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.

void

PL_fatal_error( format, a1, ...)
  Print a message like PL_warning(), but starting with `FATAL ERROR: ' and then exits Prolog.