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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 <&lt;stdio.h>&gt;
       #include <&lt;wchar.h>&gt;

       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; 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
       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 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
              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(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.   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.

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 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 plat-
       form- 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 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 3.05 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                               2007-07-26                        WPRINTF(3)