NAME
wscanf, fwscanf,
swscanf, vwscanf,
vswscanf, vfwscanf —
wide character input format
conversion
SYNOPSIS
#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);
DESCRIPTION
The
wscanf()
family of functions read input according to the given
format as described below. This format may contain
“conversion specifiers”; the results of such conversions, if
any, are stored through a set of pointer arguments.
The
wscanf()
function reads input from the standard input stream
stdin,
fwscanf()
reads input from the supplied 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
va_start(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.
Whitespace (such as blanks, tabs, or newlines) in the
format string match any amount of whitespace,
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).
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
diouxornand the next pointer is a pointer to a char (rather than int). h- Indicates that the conversion will be one of
diouxornand the next pointer is a pointer to a short int (rather than int). l(ell)- Indicates that the conversion will be one of
diouxornand the next pointer is a pointer to a long int (rather than int), that the conversion will be one ofaefgand the next pointer is a pointer to double (rather than float), or that the conversion will be one ofcorsand 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
diouxornand the next pointer is a pointer to a long long int (rather than int). L- Indicates that the conversion will be one of
aefgand the next pointer is a pointer to long double. j- Indicates that the conversion will be one of
diouxornand the next pointer is a pointer to an intmax_t (rather than int). t- Indicates that the conversion will be one of
diouxornand the next pointer is a pointer to a ptrdiff_t (rather than int). z- Indicates that the conversion will be one of
diouxornand the next pointer is a pointer to a size_t (rather than int). q- (deprecated) Indicates that the conversion will be one of
diouxornand 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 whitespace; this whitespace 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.
xX- 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
lorLis specified.) s- Matches a sequence of non-whitespace wide characters; the next pointer
must be a pointer to char, and the provided array
must be large enough to accept and store the multibyte representation of
the whole sequence and the terminating NUL character. The input string
stops at whitespace or at the maximum field width, whichever occurs first.
If specified, the maximum field length refers to the sequence being
scanned rather than the storage space, hence the provided array must be 1
larger for the terminating NUL character.
If an
lqualifier is present, the next pointer must be a pointer to wchar_t, into which the input will be placed. c- Matches a sequence of wide characters consuming the number of wide
characters specified by the field width (defaults to 1 if unspecified);
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
whitespace is suppressed. To skip whitespace first, use an explicit space
in the format.
If an
lqualifier is present, the next pointer must be a pointer to wchar_t, into which the input will be placed. [- 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 whitespace 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 ofwscanf() use “A-Z” to represent the range of characters between ‘A’ and ‘Z’. The string ends with the appearance of a character not in (or, with a circumflex, in) the set or when the field width runs out.If an
lqualifier 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.
For backwards compatibility, a “conversion” of
‘%\0’ causes an immediate 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
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 end-of-file occurs. If an error or end-of-file
occurs after conversion has begun, the number of conversions which were
successfully completed is returned.
SEE ALSO
fgetwc(3), scanf(3), wcrtomb(3), wcstod(3), wcstol(3), wcstoul(3), wprintf(3)
STANDARDS
The functions wscanf(),
fwscanf(), swscanf(),
vwscanf(), vfwscanf(), and
vswscanf() conform to ISO/IEC
9899:1999 (“ISO C99”).
CAVEATS
On systems other than OpenBSD, the
LC_NUMERIC
locale(1)
category can cause parsing failures; see CAVEATS in
setlocale(3) for details.
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
(‘%[’).