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-charac‐
ter 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 com‐
posed 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$, where n is a decimal integer in the range [1, NL_ARGMAX], giving
the position of the argument in the argument list. This feature pro‐
vides for the definition of format wide-character strings that select
arguments in an order appropriate to specific languages (see the EXAM‐
PLES section).
In format wide-character strings containing the %n$ form of conversion
specifications, numbered arguments in the argument list can be refer‐
enced 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 lan‐
guage-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$, after which the following appear in
sequence:
· Zero or more flags (in any order), which modify the meaning of the
conversion specification.
· An optional minimum field width. If the converted value has fewer
wide-characters than the field width, it will be padded with spa‐
ces by default on the left; it will be padded on the right, if the
left-adjustment flag (−), described below, is given to the field
width. The field width takes the form of an asterisk (*),
described below, or a decimal integer.
· An optional precision that gives the minimum number of digits to
appear for the d, i, o, u, x, and X conversions; the number of
digits to appear after the radix character for the a, A, e, E, f,
and F conversions; the maximum number of significant digits for
the g and G conversions; or the maximum number of wide-characters
to be printed from a string in s conversions. The precision takes
the form of a period (.) followed by either an asterisk (*),
described below, or an optional decimal digit string, where a null
digit string is treated as 0. If a precision appears with any
other conversion wide-character, the behavior is undefined.
· An optional length modifier that specifies the size of the argu‐
ment.
· A conversion specifier wide character that indicates the type of
conversion to be applied.
A field width, or precision, or both, may be indicated by an asterisk
(*). In this case an argument of type int supplies the field width or
precision. Arguments specifying field width, or precision, or both must
appear in that order before the argument, if any, to be converted. A
negative field width is taken as a − flag followed by a positive field
width. A negative precision is taken as if the precision were omitted.
In format wide-character strings containing the %n$ form of a conver‐
sion specification, a field width or precision may be indicated by the
sequence *m$, where m is a decimal integer in the range [1, NL_ARGMAX]
giving the position in the argument list (after the format argument) of
an integer argument containing the field width or precision, for exam‐
ple:
wprintf(L"%1$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 unde‐
fined. 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 conver‐
sion (%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-justi‐
fied 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 fol‐
lows 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 con‐
versions, 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 unde‐
fined.
The length modifiers and their meanings:
hh Specifies that a following d, i, o, u, x, or X conver‐
sion 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 argu‐
ment.
h Specifies that a following d, i, o, u, x, or X conver‐
sion specifier applies to a short or unsigned short
argument (the argument will have been promoted accord‐
ing 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 conver‐
sion specifier applies to a long or unsigned long argu‐
ment; 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 conver‐
sion specifier applies to a long long or unsigned long
long argument; or that a following n conversion speci‐
fier applies to a pointer to a long long argument.
j Specifies that a following d, i, o, u, x, or X conver‐
sion 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 conver‐
sion 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 conver‐
sion specifier applies to a ptrdiff_t or the corre‐
sponding 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 for‐
mat 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 lead‐
ing zeros. The default precision is 1. The result of convert‐
ing 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 lead‐
ing zeros. The default precision is 1. The result of convert‐
ing 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 speci‐
fication. 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 con‐
version is not exact, an inexact exception is raised.
For the f specifier, a double argument representing an infin‐
ity or NaN is converted in the style of the e conversion spec‐
ifier, 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 infin‐
ity 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 miss‐
ing, 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 con‐
version 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 repre‐
senting an infinity is printed as "[−]infin‐
ity", when the precision for the conversion is
at least 7 and as "[−]inf" otherwise. A dou‐
ble argument representing a NaN is printed as
"[−]nan". For the E specifier, "INF", "INFIN‐
ITY", 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 repre‐
senting 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 dig‐
its. 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 con‐
version is less than −4 or greater than or equal to the preci‐
sion. Trailing zeros are removed from the fractional portion
of the result; a radix character appears only if it is fol‐
lowed 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 "Infin‐
ity" 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 con‐
verted in the style "[-]0xh.hhhhp±d", where the single hexa‐
decimal digit preceding the radix point is 0 if the value con‐
verted 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 conver‐
sion 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 speci‐
fier 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 for‐
mat according to the prevailing floating point rounding direc‐
tion mode. If the conversion is not exact, an inexact excep‐
tion 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 con‐
verted to a wide-character as if by calling the btowc(3C)
function and the resulting wide-character is written. Other‐
wise 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 con‐
verted, 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-charac‐
ters.
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 argu‐
ment 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. Charac‐
ters 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-charac‐
ter string:
L"%1$s, %3$d. %2$s, %4$d:%5$.2d\n"
producing the message:
Sonntag, 3. Juli, 10:02
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe with exceptions │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSObtowc(3C), fputwc(3C), fwscanf(3C), mbrtowc(3C), setlocale(3C),
attributes(5), standards(5)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 com‐
piled using c89 on releases prior to Solaris 10 will experience unde‐
fined behavior.
SunOS 5.10 1 Nov 2003 fwprintf(3C)
