wscanf(3)

NAME

wscanf, fwscanf, swscanf, vwscanf, vswscanf, vfwscanf - wide
character
input format conversion

LIBRARY

Standard C Library (libc, -lc)

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 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 stan
dard 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 argu
ment list of
pointers (see stdarg(3)). The vwscanf() function scans a
variable argument list from the standard input and the vswscanf() func
tion 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 con
tain 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).

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 conversion will be
one of c or s
and the next pointer is a pointer to an ar
ray 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 con
version. 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 wc
stod(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 (de
fault 1); the
next pointer must be a pointer to char, and there must
be enough
room for the multibyte representation of all the char
acters (no
terminating NUL is added). The usual skip of leading
white space
is suppressed. To skip white space first, use an ex
plicit 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 point
er to char,
and there must be enough room for the multibyte repre
sentation 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 particu
lar 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 appear
ance 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 lo
cale (category
LC_NUMERIC).
For backwards compatibility, a ``conversion'' of `% ' 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 in
put 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.

SEE ALSO

fgetwc(3), scanf(3), wcrtomb(3), wcstod(3), wcstol(3), wc
stoul(3),
wprintf(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
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