fwide(3)

1FWIDE(3)                   Linux Programmer's Manual                  FWIDE(3)
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NAME

6       fwide - set and determine the orientation of a FILE stream
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SYNOPSIS

9       #include <wchar.h>
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11       int fwide(FILE *stream, int mode);
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13   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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15       fwide(): _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or cc -std=c99
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DESCRIPTION

18       When mode is zero, the fwide() function determines the current orienta‐
19       tion of stream.  It returns a positive value if stream is  wide-charac‐
20       ter  oriented, that is, if wide-character I/O is permitted but char I/O
21       is disallowed.  It returns a negative value if stream is byte oriented,
22       i.e.,  if  char  I/O is permitted but wide-character I/O is disallowed.
23       It returns zero if stream has no orientation yet; in this case the next
24       I/O operation might change the orientation (to byte oriented if it is a
25       char I/O operation, or to wide-character oriented if it is a wide-char‐
26       acter I/O operation).
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28       Once  a  stream  has  an orientation, it cannot be changed and persists
29       until the stream is closed.
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31       When mode is non-zero, the  fwide()  function  first  attempts  to  set
32       stream's  orientation  (to  wide-character  oriented if mode is greater
33       than 0, or to byte oriented if mode is less than 0).  It then returns a
34       value denoting the current orientation, as above.
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RETURN VALUE

37       The  fwide()  function returns the stream's orientation, after possibly
38       changing it.  A positive return value means wide-character oriented.  A
39       negative  return  value  means  byte  oriented.  A return value of zero
40       means undecided.
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CONFORMING TO

43       C99, POSIX.1-2001.
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NOTES

46       Wide-character output to  a  byte  oriented  stream  can  be  performed
47       through the fprintf(3) function with the %lc and %ls directives.
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49       Char  oriented  output  to a wide-character oriented stream can be per‐
50       formed through the fwprintf(3) function with the %c and %s directives.
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COLOPHON

56       This page is part of release 3.22 of the Linux  man-pages  project.   A
57       description  of  the project, and information about reporting bugs, can
58       be found at http://www.kernel.org/doc/man-pages/.
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62GNU                               2007-07-26                          FWIDE(3)