DragonFly On-Line Manual Pages
WSCANF(3) DragonFly Library Functions Manual 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 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).
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 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), or that the conversion will be one of
a, e, f, or g and the next pointer is a pointer to long
double (non-standard).
L Indicates that the conversion will be one of a, e, f, or
g and the next pointer is a pointer to long double, or
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) (non-standard).
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, L or ll 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.
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 fwscanf(), wscanf(), swscanf(), vfwscanf(), vwscanf() and vswscanf()
functions conform to ISO/IEC 9899:1999 ("ISO C99").
As an extension, DragonFly treats the length modifiers ll and L as
synonyms, so that the non-standard %Ld is equivalent to %ld and the non-
standard %llg is equivalent to %Lg.
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 (`%[').
DragonFly 6.3-DEVELOPMENT March 21, 2022 DragonFly 6.3-DEVELOPMENT