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 point-
ers (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).
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 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 assign-
ment 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 charac-
ters if the first character after the open bracket is a circumflex ^. To include a close bracket in the set, make it the first charac-
ter 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 '% ' 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 success-
fully completed 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 char-
acter class conversion ('%[').
BSD
July 5, 2003 BSD