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 ||
	   _POSIX_C_SOURCE >= 200112L

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
       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:

       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 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'').  If a pre-
	      cision 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  speci-
	      fied,  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.

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.

ATTRIBUTES

       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() |		 |		  |
       +-------------------------+---------------+----------------+

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, 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  platform-  and locale-dependent.  (The glibc 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 internation-
       alized  programs, the format string should consist of ASCII wide characters only, or should be constructed at run time in an international-
       ized 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 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU
								    2017-09-15								WPRINTF(3)