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NAME |LIBRARY |SYNOPSIS |DESCRIPTION |RETURN VALUE |ERRORS |ATTRIBUTES |STANDARDS |HISTORY |NOTES |SEE ALSO |COLOPHON | |
wprintf(3) Library Functions Manualwprintf(3)wprintf, fwprintf, swprintf, vwprintf, vfwprintf, vswprintf - formatted wide-character output conversion
Standard C library (libc,-lc)
#include <stdio.h>#include <wchar.h>int wprintf(const wchar_t *restrictformat, ...);int fwprintf(FILE *restrictstream,const wchar_t *restrictformat, ...);int swprintf(size_t n;wchar_twcs[restrictn], size_tn,const wchar_t *restrictformat, ...);int vwprintf(const wchar_t *restrictformat, va_listargs);int vfwprintf(FILE *restrictstream,const wchar_t *restrictformat, va_listargs);int vswprintf(size_t n;wchar_twcs[restrictn], size_tn,const wchar_t *restrictformat, va_listargs); Feature Test Macro Requirements for glibc (seefeature_test_macros(7)): All functions shown above: _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
Thewprintf() family of functions is the wide-character equivalent of theprintf(3) family of functions. It performs formatted output of wide characters. Thewprintf() andvwprintf() functions perform wide-character output tostdout.stdout must not be byte oriented; seefwide(3) for more information. Thefwprintf() andvfwprintf() functions perform wide-character output tostream.stream must not be byte oriented; seefwide(3) for more information. Theswprintf() andvswprintf() functions perform wide-character output to an array of wide characters. The programmer must ensure that there is room for at leastn wide characters atwcs. These functions are like theprintf(3),vprintf(3),fprintf(3),vfprintf(3),sprintf(3),vsprintf(3) functions except for the following differences:•Theformat string is a wide-character string.•The output consists of wide characters, not bytes.• swprintf() andvswprintf() take an argument,sprintf(3) andvsprintf(3) do not. (snprintf(3) andvsnprintf(3) take an argument, but these functions do not return -1 upon buffer overflow on Linux.) The treatment of the conversion characterscandsis different:cIf nolmodifier is present, theint argument is converted to a wide character by a call to thebtowc(3) function, and the resulting wide character is written. If anlmodifier is present, thewint_t (wide character) argument is written.sIf nolmodifier is present: theconst 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 thembrtowc(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 ofwide characters written, not the number ofbytes orscreen 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 anlmodifier is present: theconst 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.The functions return the number of wide characters written, excluding the terminating null wide character in case of the functionsswprintf() andvswprintf(). On error, -1 is returned, anderrno is set to indicate the error.
Seewrite(2) andputwc(3). In addition, the following error may occur:EOVERFLOW The value to be returned is greater thanINT_MAX. Thefwprintf() andwprintf() functions may fail additionally if:ENOMEMInsufficient storage space is available.
For an explanation of the terms used in this section, seeattributes(7). ┌───────────────────────────────┬───────────────┬────────────────┐ │Interface│Attribute│Value│ ├───────────────────────────────┼───────────────┼────────────────┤ │wprintf(),fwprintf(), │ Thread safety │ MT-Safe locale │ │swprintf(),vwprintf(), │ │ │ │vfwprintf(),vswprintf() │ │ │ └───────────────────────────────┴───────────────┴────────────────┘
C11, POSIX.1-2008.
POSIX.1-2001, C99.
The behavior ofwprintf() et al. depends on theLC_CTYPEcategory of the current locale. If theformat string contains non-ASCII wide characters, the program will work correctly only if theLC_CTYPEcategory of the current locale at run time is the same as theLC_CTYPEcategory of the current locale at compile time. This is because thewchar_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, theformat string should consist of ASCII wide characters only, or should be constructed at run time in an internationalized way (e.g., usinggettext(3) oriconv(3), followed bymbstowcs(3)).
fprintf(3),fputwc(3),fwide(3),printf(3),snprintf(3)
This page is part of theman-pages (Linux kernel and C library user-space interface documentation) project. Information about the project can be found at ⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report for this manual page, see ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩. This page was obtained from the tarball man-pages-6.15.tar.gz fetched from ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on 2025-08-11. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orgLinux man-pages 6.15 2025-06-28wprintf(3)Pages that refer to this page:fwide(3), printf(3), printf.h(3head)
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