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WPRINTF
!!!WPRINTF
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
CONFORMING TO
SEE ALSO
NOTES
----
!!NAME


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


__#include
__ ''format''__, ...);
int fwprintf (FILE*__ ''stream''__, const wchar_t*__ ''format''__, ...);
int swprintf (wchar_t*__ ''wcs''__, size_t__ ''maxlen''__,
const wchar_t*__ ''format''__, ...);
#include
__ ''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
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
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__).
----
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Last edited on Tuesday, June 4, 2002 12:24:42 am by "perry"
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