FWPRINTF(3C) Standard C Library Functions FWPRINTF(3C)

NAME

fwprintf, wprintf, swprintf - print formatted wide-character output

SYNOPSIS

#include <stdio.h>
#include <wchar.h>

int fwprintf(FILE *restrict stream, const wchar_t *restrict format,
...);


int wprintf(const wchar_t *restrict format, ...);


int swprintf(wchar_t *restrict s, size_t n, const wchar_t *restrict format,
...);

DESCRIPTION

The fwprintf() function places output on the named output stream. The
wprintf() function places output on the standard output stream stdout.
The swprintf() function places output followed by the null wide-character
in consecutive wide-characters starting at *s; no more than n wide-
characters are written, including a terminating null wide-character,
which is always added (unless n is zero).


Each of these functions converts, formats and prints its arguments under
control of the format wide-character string. The format is composed of
zero or more directives: ordinary wide-characters, which are simply
copied to the output stream and conversion specifications, each of which
results in the fetching of zero or more arguments. The results are
undefined if there are insufficient arguments for the format. If the
format is exhausted while arguments remain, the excess arguments are
evaluated but are otherwise ignored.


Conversions can be applied to the nth argument after the format in the
argument list, rather than to the next unused argument. In this case, the
conversion wide-character % (see below) is replaced by the sequence %n$,
where n is a decimal integer in the range [1, NL_ARGMAX], giving the
position of the argument in the argument list. This feature provides for
the definition of format wide-character strings that select arguments in
an order appropriate to specific languages (see the EXAMPLES section).


In format wide-character strings containing the %n$ form of conversion
specifications, numbered arguments in the argument list can be referenced
from the format wide-character string as many times as required.


In format wide-character strings containing the % form of conversion
specifications, each argument in the argument list is used exactly once.


All forms of the fwprintf() functions allow for the insertion of a
language-dependent radix character in the output string, output as a
wide-character value. The radix character is defined in the program's
locale (category LC_NUMERIC). In the POSIX locale, or in a locale where
the radix character is not defined, the radix character defaults to a
period (.).


Each conversion specification is introduced by the % wide-character or by
the wide-character sequence %n$, after which the following appear in
sequence:

o Zero or more flags (in any order), which modify the meaning of
the conversion specification.

o An optional minimum field width. If the converted value has
fewer wide-characters than the field width, it will be padded
with spaces by default on the left; it will be padded on the
right, if the left-adjustment flag (-), described below, is
given to the field width. The field width takes the form of an
asterisk (*), described below, or a decimal integer.

o An optional precision that gives the minimum number of digits
to appear for the d, i, o, u, x, and X conversions; the number
of digits to appear after the radix character for the a, A, e,
E, f, and F conversions; the maximum number of significant
digits for the g and G conversions; or the maximum number of
wide-characters to be printed from a string in s conversions.
The precision takes the form of a period (.) followed by
either an asterisk (*), described below, or an optional
decimal digit string, where a null digit string is treated as
0. If a precision appears with any other conversion wide-
character, the behavior is undefined.

o An optional length modifier that specifies the size of the
argument.

o A conversion specifier wide character that indicates the type
of conversion to be applied.


A field width, or precision, or both, may be indicated by an asterisk
(*). In this case an argument of type int supplies the field width or
precision. Arguments specifying field width, or precision, or both must
appear in that order before the argument, if any, to be converted. A
negative field width is taken as a - flag followed by a positive field
width. A negative precision is taken as if the precision were omitted. In
format wide-character strings containing the %n$ form of a conversion
specification, a field width or precision may be indicated by the
sequence *m$, where m is a decimal integer in the range [1, NL_ARGMAX]
giving the position in the argument list (after the format argument) of
an integer argument containing the field width or precision, for example:

wprintf(L"%1$d:%2$.*3$d:%4$.*3$d\n", hour, min, precision, sec);


The format can contain either numbered argument specifications (that is,
%n$ and *m$), or unnumbered argument specifications (that is, % and *),
but normally not both. The only exception to this is that %% can be mixed
with the %n$ form. The results of mixing numbered and unnumbered argument
specifications in a format wide-character string are undefined. When
numbered argument specifications are used, specifying the Nth argument
requires that all the leading arguments, from the first to the (N-1)th,
are specified in the format wide-character string.


The flag wide-characters and their meanings are:

'
The integer portion of the result of a decimal conversion (%i,
%d, %u, %f, %F, %g, or %G) will be formatted with thousands'
grouping wide-characters. For other conversions the behavior is
undefined. The non-monetary grouping wide-character is used.


-
The result of the conversion will be left-justified within the
field. The conversion will be right-justified if this flag is
not specified.


+
The result of a signed conversion will always begin with a sign
(+ or -). The conversion will begin with a sign only when a
negative value is converted if this flag is not specified.


space
If the first wide-character of a signed conversion is not a sign
or if a signed conversion results in no wide-characters, a space
will be prefixed to the result. This means that if the space and
+ flags both appear, the space flag will be ignored.


#
This flag specifies that the value is to be converted to an
alternative form. For o conversion, it increases the precision
(if necessary) to force the first digit of the result to be 0.
For x or X conversions, a non-zero result will have 0x (or 0X)
prefixed to it. For a, A, e, E, f, F, g, or G conversions, the
result will always contain a radix character, even if no digits
follow it. Without this flag, a radix character appears in the
result of these conversions only if a digit follows it. For g
and G conversions, trailing zeros will not be removed from the
result as they normally are. For other conversions, the behavior
is undefined.


0
For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions,
leading zeros (following any indication of sign or base) are
used to pad to the field width; no space padding is performed.
If the 0 and - flags both appear, the 0 flag will be ignored.
For d, i, o, u, x, and X conversions, if a precision is
specified, the 0 flag will be ignored. If the 0 and ' flags both
appear, the grouping wide-characters are inserted before zero
padding. For other conversions, the behavior is undefined.


The length modifiers and their meanings:

hh
Specifies that a following d, i, o, u, x, or X conversion
specifier applies to a signed char or unsigned char
argument (the argument will have been promoted according
to the integer promotions, but its value shall be
converted to signed char or unsigned char before
printing); or that a following n conversion specifier
applies to a pointer to a signed char argument.


h
Specifies that a following d, i, o, u, x, or X conversion
specifier applies to a short or unsigned short argument
(the argument will have been promoted according to the
integer promotions, but its value shall be converted to
short or unsigned short before printing); or that a
following n conversion specifier applies to a pointer to
a short argument.


l (ell)
Specifies that a following d, i, o, u, x, or X conversion
specifier applies to a long or unsigned long argument;
that a following n conversion specifier applies to a
pointer to a long argument; that a following c conversion
specifier applies to a wint_t argument; that a following
s conversion specifier applies to a pointer to a wchar_t
argument; or has no effect on a following a, A, e, E, f,
F, g, or G conversion specifier.


ll (ell-ell)
Specifies that a following d, i, o, u, x, or X conversion
specifier applies to a long long or unsigned long long
argument; or that a following n conversion specifier
applies to a pointer to a long long argument.


j
Specifies that a following d, i, o, u, x, or X conversion
specifier applies to an intmax_t or uintmax_t argument;
or that a following n conversion specifier applies to a
pointer to an intmax_t argument.


z
Specifies that a following d, i, o, u, x, or X conversion
specifier applies to a size_t or the corresponding signed
integer type argument; or that a following n conversion
specifier applies to a pointer to a signed integer type
corresponding to size_t argument.


t
Specifies that a following d, i, o, u, x, or X conversion
specifier applies to a ptrdiff_t or the corresponding
unsigned type argument; or that a following n conversion
specifier applies to a pointer to a ptrdiff_t argument.


L
Specifies that a following a, A, e, E, f, F, g, or G
conversion specifier applies to a long double argument.


If a length modifier appears with any conversion specifier other than as
specified above, the behavior is undefined.


The conversion wide-characters and their meanings are:

d, i
The int argument is converted to a signed decimal in the style
[-]dddd. The precision specifies the minimum number of digits to
appear; if the value being converted can be represented in fewer
digits, it will be expanded with leading zeros. The default
precision is 1. The result of converting 0 with an explicit
precision of 0 is no wide-characters.


o
The unsigned int argument is converted to unsigned octal format
in the style dddd. The precision specifies the minimum number of
digits to appear; if the value being converted can be represented
in fewer digits, it will be expanded with leading zeros. The
default precision is 1. The result of converting 0 with an
explicit precision of 0 is no wide-characters.


u
The unsigned int argument is converted to unsigned decimal format
in the style dddd. The precision specifies the minimum number of
digits to appear; if the value being converted can be represented
in fewer digits, it will be expanded with leading zeros. The
default precision is 1. The result of converting 0 with an
explicit precision of 0 is no wide-characters.


x
The unsigned int argument is converted to unsigned hexadecimal
format in the style dddd; the letters abcdef are used. The
precision specifies the minimum number of digits to appear; if
the value being converted can be represented in fewer digits, it
will be expanded with leading zeros. The default precision is 1.
The result of converting 0 with an explicit precision of 0 is no
wide-characters.


X
Behaves the same as the x conversion wide-character except that
letters "ABCDEF" are used instead of "abcdef".


f, F
The double argument is converted to decimal notation in the style
[-]ddd.ddd, where the number of digits after the radix character
(see setlocale(3C)) is equal to the precision specification. If
the precision is missing it is taken as 6; if the precision is
explicitly 0 and the # flag is not specified, no radix character
appears. If a radix character appears, at least 1 digit appears
before it. The converted value is rounded to fit the specified
output format according to the prevailing floating point rounding
direction mode. If the conversion is not exact, an inexact
exception is raised.

For the f specifier, a double argument representing an infinity
or NaN is converted in the style of the e conversion specifier,
except that for an infinite argument, "infinity" or "Infinity" is
printed when the precision is at least 8 and "inf" or "Inf" is
printed otherwise.

For the F specifier, a double argument representing an infinity
or NaN is converted in the SUSv3 style of the E conversion
specifier, except that for an infinite argument, "INFINITY" is
printed when the precision is at least 8 and or "INF" is printed
otherwise.


e, E
The double argument is converted in the style [-]d.ddde+-dd,
where there is one digit before the radix character (which is
non-zero if the argument is non-zero) and the number of digits
after it is equal to the precision; if the precision is missing,
it is taken as 6; if the precision is 0 and no # flag is present,
no radix character appears. The converted value is rounded to fit
the specified output format according to the prevailing floating
point rounding direction mode. If the conversion is not exact, an
inexact exception is raised. The E conversion wide-character will
produce a number with E instead of e introducing the exponent.
The exponent always contains at least two digits. If the value is
0, the exponent is 0.

Infinity and NaN values are handled in one of the following ways:

SUSv3
For the e specifier, a double argument representing an
infinity is printed as "[-]infinity", when the
precision for the conversion is at least 7 and as
"[-]inf" otherwise. A double argument representing a
NaN is printed as "[-]nan". For the E specifier,
"INF", "INFINITY", and "NAN" are printed instead of
"inf", "infinity", and "nan", respectively. Printing
of the sign follows the rules described above.


Default
A double argument representing an infinity is printed
as "[-]Infinity", when the precision for the
conversion is at least 7 and as "[-]Inf" otherwise. A
double argument representing a NaN is printed as
"[-]NaN". Printing of the sign follows the rules
described above.


g, G
The double argument is converted in the style f or e (or in the
style E in the case of a G conversion wide-character), with the
precision specifying the number of significant digits. If an
explicit precision is 0, it is taken as 1. The style used depends
on the value converted; style e (or E ) will be used only if the
exponent resulting from such a conversion is less than -4 or
greater than or equal to the precision. Trailing zeros are
removed from the fractional portion of the result; a radix
character appears only if it is followed by a digit.

A double argument representing an infinity or NaN is converted in
the style of the e or E conversion specifier, except that for an
infinite argument, "infinity", "INFINITY", or "Infinity" is
printed when the precision is at least 8 and "inf", "INF", or
"Inf" is printed otherwise.


a, A
A double argument representing a floating-point number is
converted in the style "[-]0xh.hhhhp+-d", where the single
hexadecimal digit preceding the radix point is 0 if the value
converted is zero and 1 otherwise and the number of hexadecimal
digits after it are equal to the precision; if the precision is
missing, the number of digits printed after the radix point is 13
for the conversion of a double value, 16 for the conversion of a
long double value on x86, and 28 for the conversion of a long
double value on SPARC; if the precision is zero and the '#' flag
is not specified, no decimal-point wide character appears. The
letters "abcdef" are used for a conversion and the letters
"ABCDEF" for A conversion. The A conversion specifier produces a
number with 'X' and 'P' instead of 'x' and 'p'. The exponent
always contains at least one digit, and only as many more digits
as necessary to represent the decimal exponent of 2. If the value
is zero, the exponent is zero.

The converted valueis rounded to fit the specified output format
according to the prevailing floating point rounding direction
mode. If the conversion is not exact, an inexact exception is
raised.

A double argument representing an infinity or NaN is converted in
the SUSv3 style of an e or E conversion specifier.


c
If no l (ell) qualifier is present, the int argument is converted
to a wide-character as if by calling the btowc(3C) function and
the resulting wide-character is written. Otherwise the wint_t
argument is converted to wchar_t, and written.


s
If no l (ell) qualifier is present, the argument must be a
pointer to a character array containing a character sequence
beginning in the initial shift state. Characters from the array
are converted as if by repeated calls to the mbrtowc(3C)
function, with the conversion state described by an mbstate_t
object initialized to zero before the first character is
converted, and written up to (but not including) the terminating
null wide-character. If the precision is specified, no more than
that many wide-characters are written. If the precision is not
specified or is greater than the size of the array, the array
must contain a null wide-character.

If an l (ell) qualifier is present, the argument must be a
pointer to an array of type wchar_t. Wide characters from the
array are written up to (but not including) a terminating null
wide-character. If no precision is specified or is greater than
the size of the array, the array must contain a null wide-
character. If a precision is specified, no more than that many
wide-characters are written.


p
The argument must be a pointer to void. The value of the pointer
is converted to a sequence of printable wide-characters.


n
The argument must be a pointer to an integer into which is
written the number of wide-characters written to the output so
far by this call to one of the fwprintf() functions. No argument
is converted.


C
Same as lc.


S
Same as ls.


%
Output a % wide-character; no argument is converted. The entire
conversion specification must be %%.


If a conversion specification does not match one of the above forms, the
behavior is undefined.


In no case does a non-existent or small field width cause truncation of a
field; if the result of a conversion is wider than the field width, the
field is simply expanded to contain the conversion result. Characters
generated by fwprintf() and wprintf() are printed as if fputwc(3C) had
been called.


The st_ctime and st_mtime fields of the file will be marked for update
between the call to a successful execution of fwprintf() or wprintf() and
the next successful completion of a call to fflush(3C) or fclose(3C) on
the same stream or a call to exit(3C) or abort(3C).

RETURN VALUES

Upon successful completion, these functions return the number of wide-
characters transmitted excluding the terminating null wide-character in
the case of swprintf() or a negative value if an output error was
encountered.


If n or more wide characters were requested to be written, swprintf()
returns a negative value.

ERRORS

For the conditions under which fwprintf() and wprintf() will fail and may
fail, refer to fputwc(3C).


In addition, all forms of fwprintf() may fail if:

EILSEQ
A wide-character code that does not correspond to a valid
character has been detected.


EINVAL
There are insufficient arguments.


In addition, wprintf() and fwprintf() may fail if:

ENOMEM
Insufficient storage space is available.

EXAMPLES

Example 1: Print Language-dependent Date and Time Format.

To print the language-independent date and time format, the following
statement could be used:


wprintf(format, weekday, month, day, hour, min);


For American usage, format could be a pointer to the wide-character
string:


L"%s, %s %d, %d:%.2d\n"


producing the message:


Sunday, July 3, 10:02


whereas for German usage, format could be a pointer to the wide-character
string:


L"%1$s, %3$d. %2$s, %4$d:%5$.2d\n"


producing the message:


Sonntag, 3. Juli, 10:02

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------------+
|Interface Stability | Standard |
+--------------------+-------------------------+
|MT-Level | MT-Safe with exceptions |
+--------------------+-------------------------+

SEE ALSO

btowc(3C), fputwc(3C), fwscanf(3C), mbrtowc(3C), setlocale(3C),
attributes(7), standards(7)

NOTES

The fwprintf(), wprintf(), and swprintf() functions can be used safely in
multithreaded applications, as long as setlocale(3C) is not being called
to change the locale.


If the j length modifier is used, 32-bit applications that were compiled
using c89 on releases prior to Solaris 10 will experience undefined
behavior.


November 1, 2003 FWPRINTF(3C)