wprintf, fwprintf, swprintf, vwprintf, vfwprintf, vswprintf — formatted wide-character output conversion
#include <stdio.h> #include <wchar.h>
int
wprintf( |
const wchar_t * | format, |
...) ; |
int
fwprintf( |
FILE * | stream, |
const wchar_t * | format, | |
...) ; |
int
swprintf( |
wchar_t * | wcs, |
size_t | maxlen, | |
const wchar_t * | format, | |
...) ; |
#include <stdarg.h>
int
vwprintf( |
const wchar_t * | format, |
va_list | args) ; |
int
vfwprintf( |
FILE * | stream, |
const wchar_t * | format, | |
va_list | args) ; |
int
vswprintf( |
wchar_t * | wcs, |
size_t | maxlen, | |
const wchar_t * | format, | |
va_list | args) ; |
The wprintf
() family of
functions is the wide-character equivalent of the printf(3) family of
functions. It performs formatted output of wide
characters.
The wprintf
() and
vwprintf
() functions perform
wide-character output to stdout
.
stdout
must not be byte
oriented; see function fwide(3) for more
information.
The fwprintf
() and
vfwprintf
() functions perform
wide-character output to stream
. stream
must not be byte
oriented; see function fwide(3) for more
information.
The swprintf
() and
vswprintf
() functions perform
wide-character output to an array of wide characters. The
programmer must ensure that there is room for at least
maxlen
wide
characters at wcs
.
These functions are like the printf(3), vprintf(3), fprintf(3), vfprintf(3), sprintf(3), vsprintf(3) functions except for the following differences:
The format
string is a wide-character string.
The output consists of wide characters, not bytes.
swprintf
() and
vswprintf
() take a
maxlen
argument, sprintf(3) and
vsprintf(3) do not.
(snprintf
(3) and vsnprintf(3) take a
maxlen
argument, but these functions do not return −1
upon buffer overflow on Linux.)
The treatment of the conversion characters c
and s
is different:
If no l
modifier is present, the int
argument is
converted to a wide character by a call to the btowc(3) function,
and the resulting wide character is written. If an
l
modifier is
present, the wint_t
(wide character)
argument is written.
If no l
modifier is present: The const char * argument is
expected to be a pointer to an array of character type
(pointer to a string) containing a multibyte character
sequence beginning in the initial shift state.
Characters from the array are converted to wide
characters (each by a call to the mbrtowc(3) function
with a conversion state starting in the initial state
before the first byte). The resulting wide characters
are written up to (but not including) the terminating
null wide character. If a precision is specified, no
more wide characters than the number specified are
written. Note that the precision determines the number
of wide
characters written, not the number of
bytes
or
screen
positions. The array must contain a
terminating null byte, unless a precision is given and
it is so small that the number of converted wide
characters reaches it before the end of the array is
reached. If an l
modifier is present:
The const wchar_t
* argument is expected to be a pointer to
an array of wide characters. Wide characters from the
array are written up to (but not including) a
terminating null wide character. If a precision is
specified, no more than the number specified are
written. The array must contain a terminating null wide
character, unless a precision is given and it is
smaller than or equal to the number of wide characters
in the array.
The functions return the number of wide characters
written, excluding the terminating null wide character in
case of the functions swprintf
() and vswprintf
(). They return −1 when an
error occurs.
The behavior of wprintf
() et
al. depends on the LC_CTYPE
category of the current locale.
If the format
string contains non-ASCII wide characters, the program will
only work correctly if the LC_CTYPE
category of the current locale at
run time is the same as the LC_CTYPE
category of the current locale at
compile time. This is because the wchar_t
representation is
platform and locale dependent. (The GNU libc represents wide
characters using their Unicode (ISO-10646) code point, but
other platforms don't do this. Also, the use of C99 universal
character names of the form \unnnn does not solve this
problem.) Therefore, in internationalized programs, the
format
string should
consist of ASCII wide characters only, or should be
constructed at run time in an internationalized way (e.g.,
using gettext(3) or iconv(3), followed by
mbstowcs(3)).
fprintf(3), fputwc(3), fwide(3), printf(3), snprintf(3)
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