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FWPRINTF(3P)		   POSIX Programmer's Manual		  FWPRINTF(3P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the	 corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.

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

SYNOPSIS
       #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, ...);

DESCRIPTION
       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 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	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 lan‐
       guages (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, specify‐
       ing 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  conver‐
       sion specification, numbered arguments in the argument list can be ref‐
       erenced	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 num‐
	  ber 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 (  '.'  )  fol‐
	  lowed 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 contain‐
       ing the "%n$" form of a conversion specification, a field width or pre‐
       cision  may  be	indicated  by the sequence "*m$", where m is a decimal
       integer in the range [1,{NL_ARGMAX}] giving the position in  the	 argu‐
       ment 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	neces‐
	      sary) 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 speci‐
	      fiers, 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  fol‐
	      lows 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 speci‐
	      fiers, 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  conver‐
	      sions, the behavior is undefined.

       The length modifiers and their meanings are:

       hh     Specifies that a following d, i, o, u, x, or X conversion speci‐
	      fier applies to a signed char or	unsigned  char	argument  (the
	      argument will have been promoted according to the integer promo‐
	      tions, 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 speci‐
	      fier 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 speci‐
	      fier applies to a long or unsigned long argument; that a follow‐
	      ing  n conversion specifier applies to a pointer to a long argu‐
	      ment; 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  fol‐
	      lowing 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 speci‐
	      fier 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 speci‐
	      fier  applies  to	 an  intmax_t or uintmax_t argument; or that a
	      following n conversion specifier applies to a pointer to an int‐
	      max_t argument.

       z      Specifies that a following d, i, o, u, x, or X conversion speci‐
	      fier 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 speci‐
	      fier 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	repre‐
	      sented 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 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 shall be expanded	 with  leading
	      zeros.  The default precision shall be 1. The result of convert‐
	      ing 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 convert‐
	      ing 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  pre‐
	      cision 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 pre‐
	      cision 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 pre‐
	      cision  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 con‐
	      version wide character shall produce a number with  'E'  instead
	      of  'e' introducing the exponent. The exponent shall always con‐
	      tain 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	 hexa‐
	      decimal  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 val‐
	      ues 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 conver‐
	      sion.  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() func‐
	      tion  and	 the resulting wide character shall be written. Other‐
	      wise, 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.	 Char‐
	      acters 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	speci‐
	      fied,  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 con‐
	      tains 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 con‐
       tains  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  man‐
	      ner.

       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.  Charac‐
       ters  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  sig‐
       nificant	 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 representa‐
       tion 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().

RETURN VALUE
       Upon successful completion, these functions shall return the number  of
       wide  characters transmitted, excluding the terminating null wide char‐
       acter 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.

ERRORS
       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 char‐
	      acter 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.

EXAMPLES
       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

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       btowc(),	 fputwc(), fwscanf(), mbrtowc(), setlocale(), the Base Defini‐
       tions volume of IEEE Std 1003.1-2001,  Chapter  7,  Locale,  <stdio.h>,
       <wchar.h>

COPYRIGHT
       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 .

IEEE/The Open Group		     2003			  FWPRINTF(3P)
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