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

BSD