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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)