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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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wprintf(3) Library Functions Manual wprintf(3)
wprintf, fwprintf, swprintf, vwprintf, vfwprintf, vswprintf -
formatted wide-character output conversion
Standard C library (libc, -lc)
#include <stdio.h>
#include <wchar.h>
int wprintf(const wchar_t *restrict format, ...);
int fwprintf(FILE *restrict stream,
const wchar_t *restrict format, ...);
int swprintf(wchar_t wcs[restrict .maxlen], size_t maxlen,
const wchar_t *restrict format, ...);
int vwprintf(const wchar_t *restrict format, va_list args);
int vfwprintf(FILE *restrict stream,
const wchar_t *restrict format, va_list args);
int vswprintf(wchar_t wcs[restrict .maxlen], size_t maxlen,
const wchar_t *restrict format, va_list args);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
All functions shown above:
_XOPEN_SOURCE >= 500 || _ISOC99_SOURCE
|| _POSIX_C_SOURCE >= 200112L
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 fwide(3)
for more information.
The fwprintf() and vfwprintf() functions perform wide-character
output to stream. stream must not be byte oriented; see 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:
c 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.
s 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 (L'\0').
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 ('\0'), 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.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────┬───────────────┬────────────────┐
│ Interface │ Attribute │ Value │
├──────────────────────────────┼───────────────┼────────────────┤
│ wprintf(), fwprintf(), │ Thread safety │ MT-Safe locale │
│ swprintf(), vwprintf(), │ │ │
│ vfwprintf(), vswprintf() │ │ │
└──────────────────────────────┴───────────────┴────────────────┘
C11, POSIX.1-2008.
POSIX.1-2001, C99.
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 work correctly only 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
glibc represents wide characters using their Unicode (ISO/IEC
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)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.9.1 2024-06-15 wprintf(3)
Pages that refer to this page: fwide(3), printf(3), printf.h(3head)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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