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NAMEorientation — the orientation of a stream DESCRIPTIONThe orientation of a stream is a property of a
FILE
object that is handled as a input/output stream.
It is useful when the input/output model assumes that characters are
handled as wide-characters within an application and stored
as multi-byte characters in files,
and that all the wide-character input/output functions begin executing
with the stream positioned at the boundary between two multi-byte characters. After a stream is associated with a file, but before any operations are
performed on the stream, the stream is without orientation.
If a wide-character input or output function is applied to a stream
without orientation, the stream becomes wide-oriented implicitly.
Likewise, if a byte input or output operation is applied to a stream
without orientation, the stream becomes byte-oriented implicitly.
Only the
fwide()
function can alter the orientation of a stream explicitly
when the stream is without orientation. Just after a stream is associated with a pipe by the
popen()
function, the stream is byte-oriented. After the stream becomes byte-oriented or wide-oriented,
the orientation of a stream will be fixed and can not be changed
until the stream is closed. The following functions are wide-character input/output functions.
fgetwc(),
fgetws(),
fputwc(),
fputws(),
fwprintf(),
fwscanf(),
getwc(),
getwchar(),
putwc(),
putwchar(),
putws(),
ungetwc(),
vfwprintf(),
wprintf(),
wscanf().
The following functions are byte input/output functions.
fgetc(),
fgets(),
fprintf(),
fputc(),
fputs(),
fread(),
fscanf(),
fwrite(),
getc(),
getchar(),
getc_unlocked(),
getchar_unlocked(),
gets(),
getw(),
printf(),
putc(),
putchar(),
putc_unlocked(),
putchar_unlocked(),
puts(),
putw(),
scanf(),
ungetc(),
vfprintf(),
vprintf().
EXAMPLESTo read characters from a stream when the orientation of the stream is unknown : int so;
wchar_t ws[CHAR_NUM];
char s[CHAR_NUM];
so = fwide(stream, 0); /* Check the orientation */
if (so > 0) /* the stream is wide-oriented */
fgetws(ws, CHAR_NUM, stream);
else if (so < 0) / * stream is byte-oriented */
fgets(s, CHAR_NUM, stream);
else /* the stream is without orientation */
fprintf(stderr, "It is first time to access this file."); WARNINGSIf byte input/output functions are applied to a wide-oriented stream or
wide-character input/output functions are applied to a byte-oriented
stream, the behavior is undefined. AUTHORThe functionality of the orientation of a stream was developed by HP and Mitsubishi Electric Corporation. SEE ALSOfgetws(3C),
fopen(3S),
fread(3S),
fwide(3C),
fwprintf(3C),
fwscanf(3C),
getc(3S),
gets(3S),
getwc(3C),
popen(3S),
printf(3S),
putc(3S),
puts(3S),
putwc(3C),
putws(3C),
scanf(3S),
ungetc(3S),
ungetwc(3C). |
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