wscanf(3) BSD Library Functions Manual wscanf(3)
NAME
fwscanf, swscanf, vfwscanf, vswscanf, vwscanf, wscanf -- wide character
input format conversion
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdio.h>
#include <wchar.h>
int
fwscanf(FILE *restrict stream, const wchar_t *restrict format, ...);
int
swscanf(const wchar_t *restrict ws, const wchar_t *restrict format, ...);
int
wscanf(const wchar_t *restrict format, ...);
#include <stdarg.h>
#include <stdio.h>
#include <wchar.h>
int
vfwscanf(FILE *restrict stream, const wchar_t *restrict format,
va_list arg);
int
vswscanf(const wchar_t *restrict ws, const wchar_t *restrict format,
va_list arg);
int
vwscanf(const wchar_t *restrict format, va_list arg);
DESCRIPTION
The wscanf() family of functions scans input, according to a format as
described below. This format may contain conversion specifiers; the
results from such conversions, if any, are stored through the pointer
arguments. The wscanf() function reads input from the standard input
stream stdin, fwscanf() reads input from the stream pointer stream, and
swscanf() reads its input from the wide character string pointed to by
ws.
The vfwscanf() function is analogous to vfwprintf(3) and reads input from
the stream pointer stream using a variable argument list of pointers (see
stdarg(3)). The vwscanf() function scans a variable argument list from
the standard input and the vswscanf() function scans it from a wide char-
acter string; these are analogous to the vwprintf() and vswprintf() func-
tions respectively. Each successive pointer argument must correspond
properly with each successive conversion specifier (but see the * conver-
sion below). All conversions are introduced by the % (percent sign)
character.
The format string may also contain other characters. White space (such
as blanks, tabs, or newlines) in the format string match any amount of
white space, including none, in the input. Everything else matches only
itself. Scanning stops when an input character does not match such a
format character. Scanning also stops when an input conversion cannot be
made (see below).
Extended locale versions of these functions are documented in
wscanf_l(3). See xlocale(3) for more information.
CONVERSIONS
Following the % character introducing a conversion, there may be a number
of flag characters, as follows:
* Suppresses assignment. The conversion that follows occurs as
usual, but no pointer is used; the result of the conversion is
simply discarded.
hh Indicates that the conversion will be one of dioux or n and the
next pointer is a pointer to a char (rather than int).
h Indicates that the conversion will be one of dioux or n and the
next pointer is a pointer to a short int (rather than int).
l (ell) Indicates that the conversion will be one of dioux or n and the
next pointer is a pointer to a long int (rather than int), that
the conversion will be one of a, e, f, or g and the next pointer
is a pointer to double (rather than float), or that the conver-
sion will be one of c or s and the next pointer is a pointer to
an array of wchar_t (rather than char).
ll (ell ell)
Indicates that the conversion will be one of dioux or n and the
next pointer is a pointer to a long long int (rather than int).
L Indicates that the conversion will be one of a, e, f, or g and
the next pointer is a pointer to long double.
j Indicates that the conversion will be one of dioux or n and the
next pointer is a pointer to a intmax_t (rather than int).
t Indicates that the conversion will be one of dioux or n and the
next pointer is a pointer to a ptrdiff_t (rather than int).
z Indicates that the conversion will be one of dioux or n and the
next pointer is a pointer to a size_t (rather than int).
q (deprecated.) Indicates that the conversion will be one of
dioux or n and the next pointer is a pointer to a long long int
(rather than int).
In addition to these flags, there may be an optional maximum field width,
expressed as a decimal integer, between the % and the conversion. If no
width is given, a default of ``infinity'' is used (with one exception,
below); otherwise at most this many characters are scanned in processing
the conversion. Before conversion begins, most conversions skip white
space; this white space is not counted against the field width.
The following conversions are available:
% Matches a literal `%'. That is, ``%%'' in the format string
matches a single input `%' character. No conversion is done, and
assignment does not occur.
d Matches an optionally signed decimal integer; the next pointer must
be a pointer to int.
i Matches an optionally signed integer; the next pointer must be a
pointer to int. The integer is read in base 16 if it begins with
`0x' or `0X', in base 8 if it begins with `0', and in base 10 oth-
erwise. Only characters that correspond to the base are used.
o Matches an octal integer; the next pointer must be a pointer to
unsigned int.
u Matches an optionally signed decimal integer; the next pointer must
be a pointer to unsigned int.
x, X Matches an optionally signed hexadecimal integer; the next pointer
must be a pointer to unsigned int.
a, A, e, E, f, F, g, G
Matches a floating-point number in the style of wcstod(3). The
next pointer must be a pointer to float (unless l or L is speci-
fied.)
s Matches a sequence of non-white-space wide characters; the next
pointer must be a pointer to char, and the array must be large
enough to accept the multibyte representation of all the sequence
and the terminating NUL character. The input string stops at white
space or at the maximum field width, whichever occurs first.
If an l qualifier is present, the next pointer must be a pointer to
wchar_t, into which the input will be placed.
S The same as ls.
c Matches a sequence of width count wide characters (default 1); the
next pointer must be a pointer to char, and there must be enough
room for the multibyte representation of all the characters (no
terminating NUL is added). The usual skip of leading white space
is suppressed. To skip white space first, use an explicit space in
the format.
If an l qualifier is present, the next pointer must be a pointer to
wchar_t, into which the input will be placed.
C The same as lc.
[ Matches a nonempty sequence of characters from the specified set of
accepted characters; the next pointer must be a pointer to char,
and there must be enough room for the multibyte representation of
all the characters in the string, plus a terminating NUL character.
The usual skip of leading white space is suppressed. The string is
to be made up of characters in (or not in) a particular set; the
set is defined by the characters between the open bracket [ charac-
ter and a close bracket ] character. The set excludes those char-
acters if the first character after the open bracket is a circum-
flex ^. To include a close bracket in the set, make it the first
character after the open bracket or the circumflex; any other posi-
tion will end the set. To include a hyphen in the set, make it the
last character before the final close bracket; some implementations
of wscanf() use ``A-Z'' to represent the range of characters
between `A' and `Z'. The string ends with the appearance of a
character not in the (or, with a circumflex, in) set or when the
field width runs out.
If an l qualifier is present, the next pointer must be a pointer to
wchar_t, into which the input will be placed.
p Matches a pointer value (as printed by `%p' in wprintf(3)); the
next pointer must be a pointer to void.
n Nothing is expected; instead, the number of characters consumed
thus far from the input is stored through the next pointer, which
must be a pointer to int. This is not a conversion, although it
can be suppressed with the * flag.
The decimal point character is defined in the program's locale (category
LC_NUMERIC).
For backwards compatibility, a ``conversion'' of `%\0' causes an immedi-
ate return of EOF.
RETURN VALUES
These functions return the number of input items assigned, which can be
fewer than provided for, or even zero, in the event of a matching fail-
ure. Zero indicates that, while there was input available, no conver-
sions were assigned; typically, this is due to an invalid input charac-
ter, such as an alphabetic character for a `%d' conversion. The value
EOF is returned if an input failure occurs before any conversion such as
an end-of-file occurs. If an error or end-of-file occurs after conver-
sion has begun, the number of conversions which were successfully com-
pleted is returned.
SEE ALSO
fgetwc(3), scanf(3), wcrtomb(3), wcstod(3), wcstol(3), wcstoul(3),
wprintf(3), wscanf_l(3)
STANDARDS
The fwscanf(), wscanf(), swscanf(), vfwscanf(), vwscanf(), and vswscanf()
functions conform to ISO/IEC 9899:1999 (``ISO C99'').
BUGS
In addition to the bugs documented in scanf(3), wscanf() does not support
the ``A-Z'' notation for specifying character ranges with the character
class conversion (`%[').
BSD July 5, 2003 BSD
Mac OS X 10.8 - Generated Sat Sep 1 07:40:30 CDT 2012