RT_RAT_NATURAL

PL_WRT_CHARESCAPES_UNICODE

PL_WRT_QUOTE_NON_ASCII

PL_WRT_PARTIAL

For example, to print a term to user_error as the toplevel does, use

    PL_write_term(Suser_error, t, 1200,
                  PL_WRT_QUOTED|PL_WRT_PORTRAY|
                  PL_WRT_VARNAMES|PL_WRT_NEWLINE)

12.9.4 Foreign stream error handling

int Sferror(IOSTREAM *s)

Returns TRUE if the stream is in an error condition, FALSE if the stream is valid and in normal condition and -1 if the stream is invalid.

void Sclearerr(IOSTREAM *s)

Clear the error state of a stream. This includes the end-of-file state, pending warnings and errors and timeout.

int Sseterr(IOSTREAM *s, int which, const char *message)

Set an error or warning state on the stream. The which argument is one of SIO_WARN or SIO_FERR. This causes PL_release_stream() to print a message (SIO_WARN) or raise an exception (SIO_FERR).

int Sset_exception(IOSTREAM *s, term_t ex)

Associate a Prolog exception term with the stream or clear the associated exception if ex is 0 and set/clear the SIO_FERR condition on the stream. If an exception is assocated PL_release_stream() raises this exception.

12.9.5 Foreign stream encoding

IOSTREAM has a field encoding that is managed at initialization from SIO_TEXT. The available encodings are defined as a C enum as below.

typedef enum
{ ENC_UNKNOWN = 0,                      /* invalid/unknown */
  ENC_OCTET,                            /* raw 8 bit input */
  ENC_ASCII,                            /* US-ASCII (0..127) */
  ENC_ISO_LATIN_1,                      /* ISO Latin-1 (0..256) */
  ENC_ANSI,                             /* default (multibyte) codepage */
  ENC_UTF8,
  ENC_UNICODE_BE,                       /* big endian unicode file */
  ENC_UNICODE_LE,                       /* little endian unicode file */
  ENC_WCHAR                             /* wchar_t */
} IOENC;

Binary streams always have the encoding ENC_OCTET. The default encoding of a text stream depends on the Prolog flag encoding. The encoding is used by all functions that perform text I/O on a stream. The encoding can be changed at any moment using