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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, ...);

       #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:

       ·      The format string is a wide character string.

       ·      The output consists of wide characters, not bytes.

       ·      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 over‐
	      flow 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 con‐
	      verted to wide characters (each by a call to the mbrtowc() func‐
	      tion  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. 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 termi‐
	      nating 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 char‐
	      acter. 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
       C99.

SEE ALSO
       fprintf(3), fputwc(3), fwide(3), printf(3), snprintf(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 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() or iconv(), followed by mbstowcs()).

GNU				  1999-11-20			    WPRINTF(3)
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