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WPRINTF(3)		   Linux Programmer's Manual		    WPRINTF(3)

NAME
       wprintf,	fwprintf, swprintf, vwprintf, vfwprintf, vswprintf - formatted
       wide-character output conversion

SYNOPSIS
       #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, ...);

       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);

   Feature Test	Macro Requirements for glibc (see feature_test_macros(7)):

       All functions shown above:
	   _XOPEN_SOURCE >= 500	|| _ISOC99_SOURCE ||
	   _ISOC95_SOURCE /* Since glibc 2.12 */ ||
	   _POSIX_C_SOURCE >= 200112L;
	   or cc -std=c99

DESCRIPTION
       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	infor-
       mation.

       The fwprintf() and vfwprintf() functions	perform	wide-character	output
       to stream.  stream must not be byte oriented; see fwide(3) for more in-
       formation.

       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),  vf-
       printf(3),  sprintf(3),	vsprintf(3) functions except for the following
       differences:

       +o      The format string	is a wide-character string.

       +o      The output consists of wide characters, not bytes.

       +o      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  buf-
	      fer 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  re-
	      sulting 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  ex-
	      pected 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 con-
	      verted 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 writ-
	      ten  up to (but not including) the terminating null wide charac-
	      ter (L'\0').  If a precision is specified, no more wide  charac-
	      ters  than the number specified are written.  Note that the pre-
	      cision 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 ter-
	      minating null wide character, unless a precision is given	and it
	      is smaller than or equal to the number of	wide characters	in the
	      array.

RETURN VALUE
       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.

CONFORMING TO
       C99.

NOTES
       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	 plat-
       form-  and locale-dependent.  (The glibc	represents wide	characters us-
       ing 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)).

SEE ALSO
       fprintf(3), fputwc(3), fwide(3),	printf(3), snprintf(3)

COLOPHON
       This  page  is  part of release 3.53 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found	at http://www.kernel.org/doc/man-pages/.

GNU				  2011-09-17			    WPRINTF(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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