1WPRINTF(3) Linux Programmer's Manual WPRINTF(3)
2
6 wprintf, fwprintf, swprintf, vwprintf, vfwprintf, vswprintf - formatted
7 wide-character output conversion
8
10 #include <stdio.h>
11 #include <wchar.h>
12 int wprintf(const wchar_t *format, ...);
14 int fwprintf(FILE *stream, const wchar_t *format, ...);
15 int swprintf(wchar_t *wcs, size_t maxlen,
16 const wchar_t *format, ...);
17 int vwprintf(const wchar_t *format, va_list args);
19 int vfwprintf(FILE *stream, const wchar_t *format, va_list args);
20 int vswprintf(wchar_t *wcs, size_t maxlen,
21 const wchar_t *format, va_list args);
22 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
24 All functions shown above: _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or
26 cc -std=c99
27
29 The wprintf() family of functions is the wide-character equivalent of
30 the printf(3) family of functions. It performs formatted output of
31 wide characters.
32 The wprintf() and vwprintf() functions perform wide-character output to
34 stdout. stdout must not be byte oriented; see fwide(3) for more infor‐
35 mation.
36 The fwprintf() and vfwprintf() functions perform wide-character output
38 to stream. stream must not be byte oriented; see fwide(3) for more
39 information.
40 The swprintf() and vswprintf() functions perform wide-character output
42 to an array of wide characters. The programmer must ensure that there
43 is room for at least maxlen wide characters at wcs.
44 These functions are like the printf(3), vprintf(3), fprintf(3),
46 vfprintf(3), sprintf(3), vsprintf(3) functions except for the following
47 differences:
48 · The format string is a wide-character string.
50 · The output consists of wide characters, not bytes.
52 · swprintf() and vswprintf() take a maxlen argument, sprintf(3)
54 and vsprintf(3) do not. (snprintf(3) and vsnprintf(3) take a
55 maxlen argument, but these functions do not return -1 upon buf‐
56 fer overflow on Linux.)
57 The treatment of the conversion characters c and s is different:
59 c If no l modifier is present, the int argument is converted to a
61 wide character by a call to the btowc(3) function, and the
62 resulting wide character is written. If an l modifier is
63 present, the wint_t (wide character) argument is written.
64 s If no l modifier is present: The const char * argument is
66 expected to be a pointer to an array of character type (pointer
67 to a string) containing a multibyte character sequence beginning
68 in the initial shift state. Characters from the array are con‐
69 verted to wide characters (each by a call to the mbrtowc(3)
70 function with a conversion state starting in the initial state
71 before the first byte). The resulting wide characters are writ‐
72 ten up to (but not including) the terminating null wide charac‐
73 ter. If a precision is specified, no more wide characters than
74 the number specified are written. Note that the precision
75 determines the number of wide characters written, not the number
76 of bytes or screen positions. The array must contain a termi‐
77 nating null byte, unless a precision is given and it is so small
78 that the number of converted wide characters reaches it before
79 the end of the array is reached. If an l modifier is present:
80 The const wchar_t * argument is expected to be a pointer to an
81 array of wide characters. Wide characters from the array are
82 written up to (but not including) a terminating null wide char‐
83 acter. If a precision is specified, no more than the number
84 specified are written. The array must contain a terminating
85 null wide character, unless a precision is given and it is
86 smaller than or equal to the number of wide characters in the
87 array.
88
90 The functions return the number of wide characters written, excluding
91 the terminating null wide character in case of the functions swprintf()
92 and vswprintf(). They return -1 when an error occurs.
93
95 C99.
96
98 The behavior of wprintf() et al. depends on the LC_CTYPE category of
99 the current locale.
100 If the format string contains non-ASCII wide characters, the program
102 will only work correctly if the LC_CTYPE category of the current locale
103 at run time is the same as the LC_CTYPE category of the current locale
104 at compile time. This is because the wchar_t representation is plat‐
105 form- and locale-dependent. (The glibc represents wide characters
106 using their Unicode (ISO-10646) code point, but other platforms don't
107 do this. Also, the use of C99 universal character names of the form
108 \unnnn does not solve this problem.) Therefore, in internationalized
109 programs, the format string should consist of ASCII wide characters
110 only, or should be constructed at run time in an internationalized way
111 (e.g., using gettext(3) or iconv(3), followed by mbstowcs(3)).
112
114 fprintf(3), fputwc(3), fwide(3), printf(3), snprintf(3)
115
117 This page is part of release 3.22 of the Linux man-pages project. A
118 description of the project, and information about reporting bugs, can
119 be found at http://www.kernel.org/doc/man-pages/.
120GNU 2007-07-26 WPRINTF(3)