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:
26 _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE ||
27 _ISOC95_SOURCE /* Since glibc 2.12 */ ||
28 _POSIX_C_SOURCE >= 200112L;
29 or cc -std=c99
30
32 The wprintf() family of functions is the wide-character equivalent of
33 the printf(3) family of functions. It performs formatted output of
34 wide characters.
35 The wprintf() and vwprintf() functions perform wide-character output to
37 stdout. stdout must not be byte oriented; see fwide(3) for more infor‐
38 mation.
39 The fwprintf() and vfwprintf() functions perform wide-character output
41 to stream. stream must not be byte oriented; see fwide(3) for more
42 information.
43 The swprintf() and vswprintf() functions perform wide-character output
45 to an array of wide characters. The programmer must ensure that there
46 is room for at least maxlen wide characters at wcs.
47 These functions are like the printf(3), vprintf(3), fprintf(3),
49 vfprintf(3), sprintf(3), vsprintf(3) functions except for the following
50 differences:
51 · The format string is a wide-character string.
53 · The output consists of wide characters, not bytes.
55 · swprintf() and vswprintf() take a maxlen argument, sprintf(3)
57 and vsprintf(3) do not. (snprintf(3) and vsnprintf(3) take a
58 maxlen argument, but these functions do not return -1 upon buf‐
59 fer overflow on Linux.)
60 The treatment of the conversion characters c and s is different:
62 c If no l modifier is present, the int argument is converted to a
64 wide character by a call to the btowc(3) function, and the
65 resulting wide character is written. If an l modifier is
66 present, the wint_t (wide character) argument is written.
67 s If no l modifier is present: The const char * argument is
69 expected to be a pointer to an array of character type (pointer
70 to a string) containing a multibyte character sequence beginning
71 in the initial shift state. Characters from the array are con‐
72 verted to wide characters (each by a call to the mbrtowc(3)
73 function with a conversion state starting in the initial state
74 before the first byte). The resulting wide characters are writ‐
75 ten up to (but not including) the terminating null wide charac‐
76 ter (L'\0'). If a precision is specified, no more wide charac‐
77 ters than the number specified are written. Note that the pre‐
78 cision determines the number of wide characters written, not the
79 number of bytes or screen positions. The array must contain a
80 terminating null byte ('\0'), unless a precision is given and it
81 is so small that the number of converted wide characters reaches
82 it before the end of the array is reached. If an l modifier is
83 present: The const wchar_t * argument is expected to be a
84 pointer to an array of wide characters. Wide characters from
85 the array are written up to (but not including) a terminating
86 null wide character. If a precision is specified, no more than
87 the number specified are written. The array must contain a ter‐
88 minating null wide character, unless a precision is given and it
89 is smaller than or equal to the number of wide characters in the
90 array.
91
93 The functions return the number of wide characters written, excluding
94 the terminating null wide character in case of the functions swprintf()
95 and vswprintf(). They return -1 when an error occurs.
96
98 C99.
99
101 The behavior of wprintf() et al. depends on the LC_CTYPE category of
102 the current locale.
103 If the format string contains non-ASCII wide characters, the program
105 will work correctly only if the LC_CTYPE category of the current locale
106 at run time is the same as the LC_CTYPE category of the current locale
107 at compile time. This is because the wchar_t representation is plat‐
108 form- and locale-dependent. (The glibc represents wide characters
109 using their Unicode (ISO-10646) code point, but other platforms don't
110 do this. Also, the use of C99 universal character names of the form
111 \unnnn does not solve this problem.) Therefore, in internationalized
112 programs, the format string should consist of ASCII wide characters
113 only, or should be constructed at run time in an internationalized way
114 (e.g., using gettext(3) or iconv(3), followed by mbstowcs(3)).
115
117 fprintf(3), fputwc(3), fwide(3), printf(3), snprintf(3)
118
120 This page is part of release 3.53 of the Linux man-pages project. A
121 description of the project, and information about reporting bugs, can
122 be found at http://www.kernel.org/doc/man-pages/.
123GNU 2011-09-17 WPRINTF(3)