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Linux 2.6 - man page for wprintf (linux section 3posix)

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

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() func-
       tion 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 char-
       acter  %  (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  specifi-
	  cation.

	* 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 preci-
	  sion 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$" form of a conver-
       sion specification, a field width or precision may be indicated	by  the  sequence  "*m$",
       where m is a decimal integer in the range [1,{NL_ARGMAX}] giving the position in the 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 conver-
	      sion 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  conver-
	      sion,  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 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 follows it. For g and G conversion specifiers, trailing zeros shall
	      not  be  removed	from the result as they normally are. For other conversion speci-
	      fiers, the behavior is undefined.

       0      For d , i , o , u , x , X , a , A , e , E , f , F , g ,  and  G  conversion  speci-
	      fiers,  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 speci-
	      fier 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 con-
	      version 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 con-
	      verted 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 charac-
	      ter 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 rep-
       resenting 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 expo-
	      nent. 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 unspec-
	      ified) 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  pre-
	      cision  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 unde-
       fined.

       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 con-
       tain 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 dec-
       imal 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 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 nega-
       tive 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 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.

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-character 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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003				      FWPRINTF(P)


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