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

NAME
       fprintf, printf, snprintf, sprintf - print formatted output

SYNOPSIS
       #include <stdio.h>

       int fprintf(FILE *restrict stream, const char *restrict format, ...);
       int printf(const char *restrict format, ...);
       int snprintf(char *restrict s, size_t n,
	      const char *restrict format, ...);
       int sprintf(char *restrict s, const char *restrict format, ...);

DESCRIPTION
       The  fprintf()  function shall place output on the named output stream.
       The printf() function shall place output on the standard output	stream
       stdout.	The sprintf() function shall place output followed by the null
       byte, '\0' , in consecutive bytes starting at  *s;  it  is  the	user's
       responsibility to ensure that enough space is available.

       The  snprintf()	function  shall	 be  equivalent to sprintf(), with the
       addition of the n argument which states the size of the buffer referred
       to  by  s.  If  n is zero, nothing shall be written and s may be a null
       pointer.	 Otherwise, output bytes beyond the n-1st shall	 be  discarded
       instead	of  being  written to the array, and a null byte is written at
       the end of the bytes actually written into the array.

       If copying takes place between objects that overlap as a	 result	 of  a
       call to sprintf() or snprintf(), the results are undefined.

       Each  of	 these	functions  converts, formats, and prints its arguments
       under control of the format. The format is a character  string,	begin‐
       ning  and ending in its initial shift state, if any. The format is com‐
       posed of zero or more directives: ordinary characters, which are simply
       copied  to  the	output	stream, and conversion specifications, each of
       which shall result in the fetching  of  zero  or	 more  arguments.  The
       results	are undefined if there are insufficient arguments for the for‐
       mat. If the format is exhausted	while  arguments  remain,  the	excess
       arguments shall be 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  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	 strings  that
       select arguments in an order appropriate to specific languages (see the
       EXAMPLES section).

       The format can contain either numbered argument	conversion  specifica‐
       tions  (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 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 string.

       In  format  strings  containing the "%n$" form of conversion specifica‐
       tion, numbered arguments in the argument list can  be  referenced  from
       the format string as many times as required.

       In  format  strings  containing the % form of conversion specification,
       each conversion specification uses the first  unused  argument  in  the
       argument list.

       All  forms of the fprintf() functions allow for the insertion of a lan‐
       guage-dependent radix character in the output string. The radix charac‐
       ter  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 '%' character	 or by
       the 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
	  bytes	 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 bytes to be printed from a string in the  s	and  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 zero. If a precision appears with any other conversion specifier,
	  the behavior is undefined.

	* An optional length modifier that specifies the size of the argument.

	* A  conversion specifier character that indicates the type of conver‐
	  sion 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 strings containing  the	 "%n$"
       form  of	 a conversion specification, a field width or precision may be
       indicated by the sequence "*m$", where m is a decimal  integer  in  the
       range  [1,{NL_ARGMAX}]  giving the position in the argument list (after
       the format argument) of an integer argument containing the field	 width
       or precision, for example:

	      printf("%1$d:%2$.*3$d:%4$.*3$d\n", hour, min, precision, sec);

       The flag 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	characters. For other conversions the behavior
	      is undefined. The non-monetary grouping character is used.

       -      The result of the conversion shall be left-justified within  the
	      field.   The  conversion	is 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 character of a signed conversion is not a  sign  or
	      if a signed conversion results in no 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 zero. 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 con‐
	      version specifiers, the result  shall  always  contain  a	 radix
	      character, even if no digits follow the radix character. Without
	      this flag, a radix character appears in the result of these con‐
	      versions	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 is ignored. For d , i , o , u , x ,  and	 X  conversion
	      specifiers,  if  a  precision  is	 specified,  the  '0'  flag is
	      ignored.	  If the '0' and '" flags both	appear,	 the  grouping
	      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
	      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 is 1. The result of converting zero with
	      an explicit precision of zero shall be no 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 is 1.   The	result	of  converting
	      zero with an explicit precision of zero shall be no 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  is 1.  The result of converting
	      zero with an explicit precision of zero shall be no 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  is
	      1.  The  result of converting zero with an explicit precision of
	      zero shall be no 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 is 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  appears  before it.  The low-order digit shall be rounded
	      in an implementation-defined manner.

       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(n-char-sequence)" or "[-]nan" ; 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 is one digit before the radix char‐
	      acter (which is non-zero if the argument is  non-zero)  and  the
	      number of digits after it is equal to the precision; if the pre‐
	      cision is missing, it shall be taken as 6; if the	 precision  is
	      zero  and	 no  '#'  flag	is  present,  no radix character shall
	      appear. The low-order digit shall be rounded in  an  implementa‐
	      tion-defined manner.  The E conversion specifier shall produce a
	      number with 'E' instead of 'e'  introducing  the	exponent.  The
	      exponent	shall always contain at least two digits. If the value
	      is zero, the exponent shall be zero.

       A double argument representing an infinity or NaN shall be converted in
       the style of an f or F conversion specifier.

       g, G   The  double  argument shall be converted in the style f or e (or
	      in the style F or E in the case of a  G  conversion  specifier),
	      with  the precision specifying the number of significant digits.
	      If an explicit precision is zero, it shall be taken  as  1.  The
	      style used depends on the value converted; style e (or E ) shall
	      be used only if the exponent resulting from such a conversion is
	      less than -4 or greater than or equal to the precision. Trailing
	      zeros shall be  removed  from  the  fractional  portion  of  the
	      result; a radix character shall appear only if it is followed by
	      a digit or a '#' flag is present.

       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  is  one
	      hexadecimal  digit (which shall be non-zero if the argument is a
	      normalized floating-point number and is  otherwise  unspecified)
	      before the decimal-point character and the number of hexadecimal
	      digits after it is 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 dou‐
	      ble, except that trailing zeros may be omitted; if the precision
	      is zero and the '#' flag	is  not	 specified,  no	 decimal-point
	      character shall appear. The letters "abcdef" shall be used for a
	      conversion and the letters "ABCDEF" for A conversion. The A con‐
	      version  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      The int argument shall be converted to an unsigned char, and the
	      resulting byte shall be written.

       If  an  l (ell) qualifier is present, the wint_t argument shall be con‐
       verted as if by an ls conversion specification with no precision and an
       argument	 that points to a two-element array of type wchar_t, the first
       element of which contains the wint_t  argument  to  the	ls  conversion
       specification and the second element contains a null wide character.

       s      The  argument shall be a pointer to an array of char. Bytes from
	      the array shall be written up to (but not including) any	termi‐
	      nating  null  byte.  If the precision is specified, no more than
	      that many bytes shall be written. If the precision is not speci‐
	      fied  or	is greater than the size of the array, the application
	      shall ensure that the array contains a null byte.

       If an l (ell) qualifier is present, the argument shall be a pointer  to
       an  array of type wchar_t. Wide characters from the array shall be con‐
       verted to characters (each as if by a call to the  wcrtomb()  function,
       with  the conversion state described by an mbstate_t object initialized
       to zero before the first wide character is converted) up to and includ‐
       ing  a  terminating null wide character. The resulting characters shall
       be written up to (but not including)  the  terminating  null  character
       (byte). If no precision is specified, the application shall ensure that
       the array contains a null wide character. If a precision is  specified,
       no  more	 than that many characters (bytes) shall be written (including
       shift sequences, if any), and the array shall contain a null wide char‐
       acter  if,  to  equal the character sequence length given by the preci‐
       sion, the function would need to access a wide character one  past  the
       end of the array. In no case shall a partial character be written.

       p      The  argument  shall  be	a  pointer  to	void. The value of the
	      pointer is converted to a sequence of printable  characters,  in
	      an implementation-defined manner.

       n      The  argument  shall  be	a  pointer to an integer into which is
	      written the number of bytes written to the output so far by this
	      call  to	one  of	 the  fprintf() functions. No argument is con‐
	      verted.

       C      Equivalent to lc .

       S      Equivalent to ls .

       %      Print a '%' character; no argument is  converted.	 The  complete
	      conversion specification shall be %% .

       If  a  conversion  specification does not match one of the above forms,
       the behavior is undefined. If any argument is not the correct type  for
       the corresponding conversion specification, the behavior is undefined.

       In no case shall 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 fprintf() and printf() are printed as if fputc()  had
       been called.

       For  the	 a  and A conversion specifiers, if FLT_RADIX is a power of 2,
       the value shall be correctly rounded to a hexadecimal  floating	number
       with the given precision.

       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  the 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 fprintf() or printf() 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, the fprintf() and printf() functions shall
       return the number of bytes transmitted.

       Upon successful completion, the sprintf()  function  shall  return  the
       number of bytes written to s, excluding the terminating null byte.

       Upon  successful	 completion,  the snprintf() function shall return the
       number of bytes that would be written to	 s  had	 n  been  sufficiently
       large excluding the terminating null byte.

       If an output error was encountered, these functions shall return a neg‐
       ative value.

       If the value of n is zero on a call to  snprintf(),  nothing  shall  be
       written,	 the  number  of bytes that would have been written had n been
       sufficiently large excluding the terminating null  shall	 be  returned,
       and s may be a null pointer.

ERRORS
       For  the	 conditions  under  which  fprintf() and printf() fail and may
       fail, refer to fputc() or fputwc() .

       In addition, all forms of fprintf() 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.

       The printf() and fprintf() functions may fail if:

       ENOMEM Insufficient storage space is available.

       The snprintf() function shall fail if:

       EOVERFLOW
	      The  value of n is greater than {INT_MAX} or the number of bytes
	      needed to hold the output	 excluding  the	 terminating  null  is
	      greater than {INT_MAX}.

       The following sections are informative.

EXAMPLES
   Printing Language-Independent Date and Time
       The following statement can be used to print date and time using a lan‐
       guage-independent format:

	      printf(format, weekday, month, day, hour, min);

       For American usage, format could be a pointer to the following string:

	      "%s, %s %d, %d:%.2d\n"

       This example would produce the following message:

	      Sunday, July 3, 10:02

       For German usage, format could be a pointer to the following string:

	      "%1$s, %3$d. %2$s, %4$d:%5$.2d\n"

       This definition of format would produce the following message:

	      Sonntag, 3. Juli, 10:02

   Printing File Information
       The following example prints information about the  type,  permissions,
       and number of links of a specific file in a directory.

       The first two calls to printf() use data decoded from a previous stat()
       call.  The user-defined strperm() function shall return a string	 simi‐
       lar  to	the  one at the beginning of the output for the following com‐
       mand:

	      ls -l

       The next call to printf() outputs the owner's name if it is found using
       getpwuid();  the	 getpwuid()  function  shall return a passwd structure
       from which the name of the user is extracted. If the user name  is  not
       found, the program instead prints out the numeric value of the user ID.

       The  next  call	prints	out  the  group name if it is found using get‐
       grgid(); getgrgid() is very similar to getpwuid() except that it	 shall
       return  group information based on the group number. Once again, if the
       group is not found, the program prints the numeric value of  the	 group
       for the entry.

       The final call to printf() prints the size of the file.

	      #include <stdio.h>
	      #include <sys/types.h>
	      #include <pwd.h>
	      #include <grp.h>

	      char *strperm (mode_t);
	      ...
	      struct stat statbuf;
	      struct passwd *pwd;
	      struct group *grp;
	      ...
	      printf("%10.10s", strperm (statbuf.st_mode));
	      printf("%4d", statbuf.st_nlink);

	      if ((pwd = getpwuid(statbuf.st_uid)) != NULL)
		  printf(" %-8.8s", pwd->pw_name);
	      else
		  printf(" %-8ld", (long) statbuf.st_uid);

	      if ((grp = getgrgid(statbuf.st_gid)) != NULL)
		  printf(" %-8.8s", grp->gr_name);
	      else
		  printf(" %-8ld", (long) statbuf.st_gid);

	      printf("%9jd", (intmax_t) statbuf.st_size);
	      ...

   Printing a Localized Date String
       The  following  example gets a localized date string. The nl_langinfo()
       function shall return the localized date string,	 which	specifies  the
       order and layout of the date. The strftime() function takes this infor‐
       mation and, using the tm structure for values, places the date and time
       information  into  datestring.  The printf() function then outputs dat‐
       estring and the name of the entry.

	      #include <stdio.h>
	      #include <time.h>
	      #include <langinfo.h>
	      ...
	      struct dirent *dp;
	      struct tm *tm;
	      char datestring[256];
	      ...
	      strftime(datestring, sizeof(datestring), nl_langinfo (D_T_FMT), tm);

	      printf(" %s %s\n", datestring, dp->d_name);
	      ...

   Printing Error Information
       The following example uses fprintf()  to	 write	error  information  to
       standard error.

       In  the	first  group  of calls, the program tries to open the password
       lock file named LOCKFILE. If the file already exists, this is an error,
       as  indicated  by  the  O_EXCL flag on the open() function. If the call
       fails, the program assumes that someone else is updating	 the  password
       file, and the program exits.

       The  next group of calls saves a new password file as the current pass‐
       word file by creating a link between LOCKFILE and the new password file
       PASSWDFILE.

	      #include <sys/types.h>
	      #include <sys/stat.h>
	      #include <fcntl.h>
	      #include <stdio.h>
	      #include <stdlib.h>
	      #include <unistd.h>
	      #include <string.h>
	      #include <errno.h>

	      #define LOCKFILE "/etc/ptmp"
	      #define PASSWDFILE "/etc/passwd"
	      ...
	      int pfd;
	      ...
	      if ((pfd = open(LOCKFILE, O_WRONLY | O_CREAT | O_EXCL,
		  S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) == -1)
	      {
		  fprintf(stderr, "Cannot open /etc/ptmp. Try again later.\n");
		  exit(1);
	      }
	      ...
	      if (link(LOCKFILE,PASSWDFILE) == -1) {
		  fprintf(stderr, "Link error: %s\n", strerror(errno));
		  exit(1);
	      }
	      ...

   Printing Usage Information
       The following example checks to make sure the program has the necessary
       arguments, and  uses  fprintf()	to  print  usage  information  if  the
       expected number of arguments is not present.

	      #include <stdio.h>
	      #include <stdlib.h>
	      ...
	      char *Options = "hdbtl";
	      ...
	      if (argc < 2) {
		  fprintf(stderr, "Usage: %s -%s <file\n", argv[0], Options); exit(1);
	      }
	      ...

   Formatting a Decimal String
       The  following  example prints a key and data pair on stdout.  Note use
       of the '*' (asterisk) in the format string; this	 ensures  the  correct
       number  of  decimal  places for the element based on the number of ele‐
       ments requested.

	      #include <stdio.h>
	      ...
	      long i;
	      char *keystr;
	      int elementlen, len;
	      ...
	      while (len < elementlen) {
	      ...
		  printf("%s Element%0*ld\n", keystr, elementlen, i);
	      ...
	      }

   Creating a Filename
       The following example creates a filename using information from a  pre‐
       vious getpwnam() function that returned the HOME directory of the user.

	      #include <stdio.h>
	      #include <sys/types.h>
	      #include <unistd.h>
	      ...
	      char filename[PATH_MAX+1];
	      struct passwd *pw;
	      ...
	      sprintf(filename, "%s/%d.out", pw->pw_dir, getpid());
	      ...

   Reporting an Event
       The  following  example loops until an event has timed out. The pause()
       function waits forever unless  it  receives  a  signal.	The  fprintf()
       statement  should  never	 occur	due  to	 the possible return values of
       pause().

	      #include <stdio.h>
	      #include <unistd.h>
	      #include <string.h>
	      #include <errno.h>
	      ...
	      while (!event_complete) {
	      ...
		  if (pause() != -1 || errno != EINTR)
		      fprintf(stderr, "pause: unknown error: %s\n", strerror(errno));
	      }
	      ...

   Printing Monetary Information
       The following example uses strfmon() to convert a number and  store  it
       as  a  formatted	 monetary string named convbuf. If the first number is
       printed, the program prints the format and the description;  otherwise,
       it just prints the number.

	      #include <monetary.h>
	      #include <stdio.h>
	      ...
	      struct tblfmt {
		  char *format;
		  char *description;
	      };

	      struct tblfmt table[] = {
		  { "%n", "default formatting" },
		  { "%11n", "right align within an 11 character field" },
		  { "%#5n", "aligned columns for values up to 99999" },
		  { "%=*#5n", "specify a fill character" },
		  { "%=0#5n", "fill characters do not use grouping" },
		  { "%^#5n", "disable the grouping separator" },
		  { "%^#5.0n", "round off to whole units" },
		  { "%^#5.4n", "increase the precision" },
		  { "%(#5n", "use an alternative pos/neg style" },
		  { "%!(#5n", "disable the currency symbol" },
	      };
	      ...
	      float input[3];
	      int i, j;
	      char convbuf[100];
	      ...
	      strfmon(convbuf, sizeof(convbuf), table[i].format, input[j]);

	      if (j == 0) {
		  printf("%s  %s  %s\n", table[i].format,
		      convbuf, table[i].description);
	      }
	      else {
		  printf("    %s\n", convbuf);
	      }
	      ...

   Printing Wide Characters
       The  following example prints a series of wide characters. Suppose that
       "L`@`" expands to three bytes:

	      wchar_t wz [3] = L"@@";	    // Zero-terminated
	      wchar_t wn [3] = L"@@@";	    // Unterminated

	      fprintf (stdout,"%ls", wz);   // Outputs 6 bytes
	      fprintf (stdout,"%ls", wn);   // Undefined because wn has no terminator
	      fprintf (stdout,"%4ls", wz);  // Outputs 3 bytes
	      fprintf (stdout,"%4ls", wn);  // Outputs 3 bytes; no terminator needed
	      fprintf (stdout,"%9ls", wz);  // Outputs 6 bytes
	      fprintf (stdout,"%9ls", wn);  // Outputs 9 bytes; no terminator needed
	      fprintf (stdout,"%10ls", wz); // Outputs 6 bytes
	      fprintf (stdout,"%10ls", wn); // Undefined because wn has no terminator

       In the last line of the example,	 after	processing  three  characters,
       nine bytes have been output. The fourth character must then be examined
       to determine whether it converts to one byte or more.  If  it  converts
       to more than one byte, the output is only nine bytes. Since there is no
       fourth character in the array, the behavior is undefined.

APPLICATION USAGE
       If the application calling fprintf() has any objects of type wint_t  or
       wchar_t,	 it  must  also	 include  the  <wchar.h>  header to have these
       objects defined.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       fputc() , fscanf() , setlocale() , strfmon() ,  wcrtomb()  ,  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			    FPRINTF(P)
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