Originální popis anglicky:
fwprintf, swprintf, wprintf - print formatted wide-character output
Návod, kniha: POSIX Programmer's Manual
#include <stdio.h>
#include <wchar.h>
int fwprintf(FILE *restrict
stream, const wchar_t
*restrict format, ...);
int swprintf(wchar_t *restrict
ws, size_t
n,
const wchar_t *restrict
format, ...);
int wprintf(const wchar_t *restrict
format, ...);
The
fwprintf() function shall place output on the named output
stream. The
wprintf() function shall place output on the
standard output stream
stdout. The
swprintf() function shall
place output followed by the null wide character in consecutive wide
characters starting at *
ws; no more than
n wide characters
shall be written, including a terminating null wide character, which is always
added (unless
n is zero).
Each of these functions shall convert, format, and print 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 specifier wide character
% (see below) is replaced by the
sequence
"%n$" , where
n is a decimal integer in the
range [1,{NL_ARGMAX}], giving the position of the argument in the argument
list. This feature provides for the definition of
format wide-character
strings that select arguments in an order appropriate to specific languages
(see the EXAMPLES section).
The
format can contain either numbered argument specifications (that is,
"%n$" and
"*m$"), or unnumbered argument conversion
specifications (that is,
% and
* ), but not both. The only
exception to this is that
%% can be mixed with the
"%n $" form. The results of mixing numbered and
unnumbered argument specifications in a
format wide-character string
are undefined. When numbered argument specifications are used, specifying the
Nth argument requires that all the leading arguments, from the first to
the (
N-1)th, are specified in the
format wide-character string.
In
format wide-character strings containing the
"%n$" form of conversion specification,
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 specification, each argument in the argument list shall be used
exactly once.
All forms of the
fwprintf() function allow for the insertion of a
locale-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 shall default to a period
(
'.' ).
Each conversion specification is introduced by the
'%' wide character
or by the wide-character sequence
"%n$", after which the following appear
in sequence:
- *
- Zero or more flags (in any order), which modify the
meaning of the conversion specification.
- *
- An optional minimum field width. If the converted
value has fewer wide characters than the field width, it shall be padded
with spaces by default on the left; it shall be padded on the right, if
the left-adjustment flag ( '-' ), described below, is given to the
field width. The field width takes the form of an asterisk ( '*' ),
described below, or a decimal integer.
- *
- An optional precision that gives the minimum number
of digits to appear for the d , i , o , u ,
x , and X conversion specifiers; the number of digits to
appear after the radix character for the a , A , e ,
E , f , and F conversion specifiers; the maximum
number of significant digits for the g and G conversion
specifiers; or the maximum number of wide characters to be printed from a
string in the s conversion specifiers. The precision takes the form
of a period ( '.' ) followed either by an asterisk ( '*' ),
described below, or an optional decimal digit string, where a null digit
string is treated as 0. If a precision appears with any other conversion
wide character, the behavior is undefined.
- *
- An optional length modifier that specifies the size of the
argument.
- *
- A conversion specifier wide character that indicates
the type of conversion to be applied.
A field width, or precision, or both, may be indicated by an asterisk (
'*' ). In this case an argument of type
int supplies the field
width or precision. Applications shall ensure that arguments specifying field
width, or precision, or both appear in that order before the argument, if any,
to be converted. A negative field width is taken as a
'-' flag followed
by a positive field width. A negative precision is taken as if the precision
were omitted. In
format wide-character strings containing the
"%n$" 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 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 ) shall be formatted with thousands' grouping wide characters.
For other conversions, the behavior is undefined. The numeric grouping
wide character is used.
- -
- The result of the conversion shall be left-justified within
the field. The conversion shall be right-justified if this flag is not
specified.
- +
- The result of a signed conversion shall always begin with a
sign ( '+' or '-' ). The conversion shall 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> shall be prefixed to the result. This means that if the
<space> and '+' flags both appear, the <space> flag
shall be ignored.
- #
- 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 conversion specifiers, a non-zero result shall have 0x (or 0X)
prefixed to it. For a , A , e , E , f ,
F , g , and G conversion specifiers, the result shall
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 conversion
specifiers, trailing zeros shall not be removed from the result as
they normally are. For other conversion specifiers, the behavior is
undefined.
- 0
- For d , i , o , u , x ,
X , a , A , e , E , f , F
, g , and G conversion specifiers, 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 shall be ignored. For d , i ,
o , u , x , and X conversion specifiers, if a
precision is specified, the '0' flag shall 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 are:
- 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 a 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 specifiers and their meanings are:
- d, i
- The int argument shall be 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 shall be expanded with
leading zeros. The default precision shall be 1. The result of converting
zero with an explicit precision of zero shall be no wide characters.
- o
- The unsigned argument shall be 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 shall be expanded with
leading zeros. The default precision shall be 1. The result of converting
zero with an explicit precision of zero shall be no wide characters.
- u
- The unsigned argument shall be 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 shall be expanded with
leading zeros. The default precision shall be 1. The result of converting
zero with an explicit precision of zero shall be no wide characters.
- x
- The unsigned argument shall be 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 shall be expanded with leading zeros. The
default precision shall be 1. The result of converting zero with an
explicit precision of zero shall be no wide characters.
- X
- Equivalent to the x conversion specifier, except
that letters "ABCDEF" are used instead of
"abcdef" .
- f, F
- The double argument shall be converted to decimal
notation in the style "[-]ddd.ddd", where the
number of digits after the radix character shall be equal to the precision
specification. If the precision is missing, it shall be taken as 6; if the
precision is explicitly zero and no '#' flag is present, no radix
character shall appear. If a radix character appears, at least one digit
shall appear before it. The value shall be rounded in an
implementation-defined manner to the appropriate number of digits.
A
double argument representing an infinity shall be converted in one of
the styles
"[-]inf" or
"[-]infinity" ; which
style is implementation-defined. A
double argument representing a NaN
shall be converted in one of the styles
"[-]nan" or
"[-]nan( n-char-sequence)"; which style, and
the meaning of any
n-char-sequence, is implementation-defined. The
F conversion specifier produces
"INF" ,
"INFINITY" , or
"NAN" instead of
"inf" ,
"infinity" , or
"nan" , respectively.
- e, E
- The double argument shall be converted in the style
"[-]d.ddde±dd", where there shall be
one digit before the radix character (which is non-zero if the argument is
non-zero) and the number of digits after it shall be equal to the
precision; if the precision is missing, it shall be taken as 6; if the
precision is zero and no '#' flag is present, no radix character
shall appear. The value shall be rounded in an implementation-defined
manner to the appropriate number of digits. The E conversion wide
character shall produce a number with 'E' instead of 'e'
introducing the exponent. The exponent shall always contain at least two
digits. If the value is zero, the exponent shall be zero.
A
double argument representing an infinity or NaN shall be converted in
the style of an
f or
F conversion specifier.
- g, G
- The double argument shall be converted in the style
f or e (or in the style F or E in the case of
a G conversion specifier), with the precision specifying the number
of significant digits. If an explicit precision is zero, it shall be taken
as 1. The style used depends on the value converted; style e (or
E ) shall 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 shall be removed from the fractional portion of the result;
a radix character shall appear only if it is followed by a digit.
A
double argument representing an infinity or NaN shall be converted in
the style of an
f or
F conversion specifier.
- a, A
- A double argument representing a floating-point
number shall be converted in the style
"[-]0xh.hhhhp±d", where there shall be one
hexadecimal digit (which is non-zero if the argument is a normalized
floating-point number and is otherwise unspecified) before the
decimal-point wide character and the number of hexadecimal digits after it
shall be equal to the precision; if the precision is missing and FLT_RADIX
is a power of 2, then the precision shall be sufficient for an exact
representation of the value; if the precision is missing and FLT_RADIX is
not a power of 2, then the precision shall be sufficient to distinguish
values of type double, except that trailing zeros may be omitted;
if the precision is zero and the '#' flag is not specified, no
decimal-point wide character shall appear. 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 shall always contain 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 shall be zero.
A
double argument representing an infinity or NaN shall be converted in
the style of an
f or
F conversion specifier.
- c
- If no l (ell) qualifier is present, the int
argument shall be converted to a wide character as if by calling the
btowc() function and the resulting wide character shall be written.
Otherwise, the wint_t argument shall be converted to
wchar_t, and written.
- s
- If no l (ell) qualifier is present, the application
shall ensure that the argument is a pointer to a character array
containing a character sequence beginning in the initial shift state.
Characters from the array shall be converted as if by repeated calls to
the mbrtowc() 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 shall be written. If the precision is not specified, or is
greater than the size of the array, the application shall ensure that the
array contains a null wide character.
If an
l (ell) qualifier is present, the application shall ensure that the
argument is a pointer to an array of type
wchar_t. Wide characters from
the array shall be 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 application shall ensure that the array contains a null wide
character. If a precision is specified, no more than that many wide characters
shall be written.
- p
- The application shall ensure that the argument is a pointer
to void. The value of the pointer shall be converted to a sequence
of printable wide characters in an implementation-defined manner.
- n
- The application shall ensure that the argument is 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 shall be converted, but one shall be consumed. If
the conversion specification includes any flags, a field width, or a
precision, the behavior is undefined.
- C
- Equivalent to lc .
- S
- Equivalent to ls .
- %
- Output a '%' wide character; no argument shall be
converted. The entire conversion specification shall be %% .
If a conversion specification does not match one of the above forms, the
behavior is undefined.
In no case does a nonexistent or small field width cause truncation of a field;
if the result of a conversion is wider than the field width, the field shall
be expanded to contain the conversion result. Characters generated by
fwprintf() and
wprintf() shall be printed as if
fputwc()
had been called.
For
a and
A conversions, if FLT_RADIX is not a power of 2 and the
result is not exactly representable in the given precision, the result should
be one of the two adjacent numbers in hexadecimal floating style with the
given precision, with the extra stipulation that the error should have a
correct sign for the current rounding direction.
For
e ,
E ,
f ,
F ,
g , and
G
conversion specifiers, if the number of significant decimal digits is at most
DECIMAL_DIG, then the result should be correctly rounded. If the number of
significant decimal digits is more than DECIMAL_DIG but the source value is
exactly representable with DECIMAL_DIG digits, then the result should be an
exact representation with trailing zeros. Otherwise, the source value is
bounded by two adjacent decimal strings
L <
U, both having
DECIMAL_DIG significant digits; the value of the resultant decimal string
D should satisfy
L <=
D <=
U, with the extra
stipulation that the error should have a correct sign for the current rounding
direction.
The
st_ctime and
st_mtime fields of the file shall 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() or
fclose() on the same stream, or a call to
exit() or
abort().
Upon successful completion, these functions shall 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, and set
errno to indicate the error.
If
n or more wide characters were requested to be written,
swprintf() shall return a negative value, and set
errno
to indicate the error.
For the conditions under which
fwprintf() and
wprintf() fail and
may fail, refer to
fputwc() .
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.
The following sections are informative.
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:
producing the message:
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:
None.
None.
None.
btowc() ,
fputwc() ,
fwscanf() ,
mbrtowc() ,
setlocale() , the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 7, Locale,
<stdio.h>,
<wchar.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
