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, ...);

       #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);

DESCRIPTION

       The  wprintf  family  of functions is the wide-character equivalent of the printf 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  for  more
       information.

       The fwprintf and vfwprintf functions perform wide character output to stream. stream must not be byte oriented; see function fwide 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, vprintf, fprintf, vfprintf, sprintf, vsprintf 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 and vsprintf do not. (snprintf and vsnprintf 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 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 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.

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

       ISO/ANSI C, UNIX98

SEE ALSO

       printf(3), fprintf(3), snprintf(3), fputwc(3), fwide(3), wscanf(3)

NOTES

       The behaviour 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 ISO C99 universal character names of the form unnnn does not solve this problem.) Therefore, in interna-
       tionalized programs, the format string should consist of ASCII wide characters only, or should be constructed at run time  in  an  interna-
       tionalized way (e.g. using gettext or iconv, followed by mbstowcs).

GNU
								    1999-11-20								WPRINTF(3)