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

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
	  number of digits to appear after the radix character for the a , A ,
	  e  , E , f , and F conversion specifiers; the maximum number of sig‐
	  nificant digits for the g and G conversion specifiers; or the	 maxi‐
	  mum  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 charac‐
	  ter, 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 con‐
       taining 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	 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 thou‐
	      sands' 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
	      specifiers,  the	result shall always contain a radix character,
	      even if no digits follow it. Without this flag, a radix  charac‐
	      ter  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 conver‐
	      sion 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 con‐
	      versions, 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 promo‐
	      tions, but its value shall be converted  to  short  or  unsigned
	      short  before printing); or that a following n conversion speci‐
	      fier 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 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
	      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 inte‐
	      ger 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 con‐
	      version 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
       significant decimal digits is at	 most  DECIMAL_DIG,  then  the	result
       should  be correctly rounded. If the number of significant decimal dig‐
       its is more than DECIMAL_DIG but the source  value  is  exactly	repre‐
       sentable	 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().

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
       Definitions   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(P)
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