wscanf, fwscanf, swscanf, vwscanf, vswscanf, vfwscanf -- wide character
input format conversion
Standard C Library (libc, -lc)
#include <stdio.h>
#include <wchar.h>
int
wscanf(const wchar_t * restrict format, ...);
int
fwscanf(FILE * restrict stream, const wchar_t * restrict format, ...);
int
swscanf(const wchar_t * restrict str, const wchar_t * restrict format,
...);
#include <stdarg.h>
int
vwscanf(const wchar_t * restrict format, va_list ap);
int
vswscanf(const wchar_t * restrict str, const wchar_t * restrict format,
va_list ap);
int
vfwscanf(FILE * restrict stream, const wchar_t * restrict format,
va_list ap);
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
str. 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 character string; these are analogous to the vwprintf() and
vswprintf() functions respectively. Each successive pointer argument
must correspond properly with each successive conversion specifier (but
see the * conversion 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).
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 conversion
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 otherwise.
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 specified.)
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 [ character
and a close bracket ] character. The set excludes those characters
if the first character after the open bracket is a circumflex
^. To include a close bracket in the set, make it the first
character after the open bracket or the circumflex; any other position
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 immediate
return of EOF.
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 failure.
Zero indicates that, while there was input available, no conversions
were assigned; typically this is due to an invalid input character,
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 endof-file
occurs. If an error or end-of-file occurs after conversion has
begun, the number of conversions which were successfully completed is
returned.
fgetwc(3), scanf(3), wcrtomb(3), wcstod(3), wcstol(3), wcstoul(3),
wprintf(3)
The fwscanf(), wscanf(), swscanf(), vfwscanf(), vwscanf() and vswscanf()
functions conform to ISO/IEC 9899:1999 (``ISO C99'').
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 (`%[').
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