.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>

.\"

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.\" This is free documentation; you can redistribute it and/or

.\" modify it under the terms of the GNU General Public License as

.\" published by the Free Software Foundation; either version 2 of

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.\"

.\" References consulted:

.\"   GNU glibc-2 source code and manual

.\"   Dinkumware C library reference http://www.dinkumware.com/

.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html

.\"   ISO/IEC 9899:1999

.\"

.TH WPRINTF 3  2017-09-15 "GNU" "Linux Programmer's Manual"

.SH NAME

wprintf, fwprintf, swprintf, vwprintf, vfwprintf, vswprintf \- formatted

wide-character output conversion

.SH SYNOPSIS

.nf

.B #include <stdio.h>

.B #include <wchar.h>

.PP

.BI "int wprintf(const wchar_t *" format ", ...);"

.BI "int fwprintf(FILE *" stream ", const wchar_t *" format ", ...);"

.BI "int swprintf(wchar_t *" wcs ", size_t " maxlen ,

.BI "             const wchar_t *" format ", ...);"

.PP

.BI "int vwprintf(const wchar_t *" format ", va_list " args );

.BI "int vfwprintf(FILE *" stream ", const wchar_t *" format ", va_list " args );

.BI "int vswprintf(wchar_t *" wcs ", size_t " maxlen ,

.BI "              const wchar_t *" format ", va_list " args );

.fi

.PP

.in -4n

Feature Test Macro Requirements for glibc (see

.BR feature_test_macros (7)):

.in

.PP

.ad l

All functions shown above:

.RS 4

.\" .BR wprintf (),

.\" .BR fwprintf (),

.\" .BR swprintf (),

.\" .BR vwprintf (),

.\" .BR vfwprintf (),

.\" .BR vswprintf ():

_XOPEN_SOURCE\ >=\ 500 || _ISOC99_SOURCE ||

.br

_POSIX_C_SOURCE\ >=\ 200112L

.RE

.ad

.SH DESCRIPTION

The

.BR wprintf ()

family of functions is

the wide-character equivalent of the

.BR printf (3)

family of functions.

It performs formatted output of wide

characters.

.PP

The

.BR wprintf ()

and

.BR vwprintf ()

functions

perform wide-character output to

.IR stdout .

.I stdout

must not be byte oriented; see

.BR fwide (3)

for more information.

.PP

The

.BR fwprintf ()

and

.BR vfwprintf ()

functions

perform wide-character output to

.IR stream .

.I stream

must not be byte oriented; see

.BR fwide (3)

for more information.

.PP

The

.BR swprintf ()

and

.BR vswprintf ()

functions

perform wide-character output

to an array of wide characters.

The programmer must ensure that there is

room for at least

.I maxlen

wide

characters at

.IR wcs .

.PP

These functions are like

the

.BR printf (3),

.BR vprintf (3),

.BR fprintf (3),

.BR vfprintf (3),

.BR sprintf (3),

.BR vsprintf (3)

functions except for the

following differences:

.TP

.B \(bu

The

.I format

string is a wide-character string.

.TP

.B \(bu

The output consists of wide characters, not bytes.

.TP

.B \(bu

.BR swprintf ()

and

.BR vswprintf ()

take a

.I maxlen

argument,

.BR sprintf (3)

and

.BR vsprintf (3)

do not.

.RB ( snprintf (3)

and

.BR vsnprintf (3)

take a

.I maxlen

argument, but these functions do not return \-1 upon

buffer overflow on Linux.)

.PP

The treatment of the conversion characters

.BR c

and

.B s

is different:

.TP

.B c

If no

.B l

modifier is present, the

.I int

argument is converted to a wide character by a call to the

.BR btowc (3)

function, and the resulting wide character is written.

If an

.B l

modifier is present, the

.I wint_t

(wide character) argument is written.

.TP

.B s

If no

.B l

modifier is present: the

.I "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

.BR 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\(aq\\0\(aq).

If a precision is

specified, no more wide characters than the number specified are written.

Note that the precision determines the number of

.I wide characters

written, not the number of

.I bytes

or

.IR "screen positions" .

The array must contain a terminating null byte (\(aq\\0\(aq),

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

.B l

modifier is present: the

.I "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.

.SH RETURN VALUE

The functions return the number of wide characters written, excluding the

terminating null wide character in

case of the functions

.BR swprintf ()

and

.BR vswprintf ().

They return \-1 when an error occurs.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lbw24 lb lb

l l l.

Interface	Attribute	Value

T{

.BR wprintf (),

.BR fwprintf (),

.br

.BR swprintf (),

.BR vwprintf (),

.br

.BR vfwprintf (),

.BR vswprintf ()

T}	Thread safety	MT-Safe locale

.TE

.sp 1

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008, C99.

.SH NOTES

The behavior of

.BR wprintf ()

et al. depends

on the

.B LC_CTYPE

category of the

current locale.

.PP

If the

.I format

string contains non-ASCII wide characters, the program

will work correctly only if the

.B LC_CTYPE

category of the current locale at

run time is the same as the

.B LC_CTYPE

category of the current locale at

compile time.

This is because the

.I wchar_t

representation is platform- 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

.I format

string should consist of ASCII

wide characters only, or should be constructed at run time in an

internationalized way (e.g., using

.BR gettext (3)

or

.BR iconv (3),

followed by

.BR mbstowcs (3)).

.SH SEE ALSO

.BR fprintf (3),

.BR fputwc (3),

.BR fwide (3),

.BR printf (3),

.BR snprintf (3)

.\" .BR wscanf (3)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.