# wprintf

## NAME



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


## LIBRARY



           Standard C library (_libc_ , _-lc_)
    


## SYNOPSIS



           **#include <stdio.h>**
           **#include <wchar.h>**
    
           **int wprintf(const wchar_t *restrict** _format_**, ...);**
           **int fwprintf(FILE *restrict** _stream_**,**
                        **const wchar_t *restrict** _format_**, ...);**
           **int swprintf(** size_t n;
                        **wchar_t** _wcs_**[restrict** _n_**], size_t** _n_**,**
                        **const wchar_t *restrict** _format_**, ...);**
    
           **int vwprintf(const wchar_t *restrict** _format_**, va_list** _args_**);**
           **int vfwprintf(FILE *restrict** _stream_**,**
                        **const wchar_t *restrict** _format_**, va_list** _args_**);**
           **int vswprintf(** size_t n;
                        **wchar_t** _wcs_**[restrict** _n_**], size_t** _n_**,**
                        **const wchar_t *restrict** _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 _n_ 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:
    
           **•** The _format_ string is a wide-character string.
    
           **•** The output consists of wide characters, not bytes.
    
           **•      swprintf**() and **vswprintf**() take a _n_ argument, sprintf(3)
                  and vsprintf(3) do not.  (snprintf(3) and vsnprintf(3) take
                  a _n_ 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'\0').  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 ('\0'), 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**().  On error, -1 is returned,
           and _errno_ is set to indicate the error.
    


## ERRORS



           See write(2) and putwc(3).  In addition, the following error may
           occur:
    
           **EOVERFLOW**
                  The value to be returned is greater than **INT_MAX**.
    
           The **fwprintf**() and **wprintf**() functions may fail additionally if:
    
           **ENOMEM** Insufficient storage space is available.
    


## 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**()      │               │                │
           └───────────────────────────────┴───────────────┴────────────────┘
    


## STANDARDS



           C11, POSIX.1-2008.
    


## 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/IEC 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)).
    


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