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FPRINTF(P)                                                          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.ddddd",  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.hhhhd", where there is one hex‐
              adecimal  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 .



POSIX                                2003                           FPRINTF(P)

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