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():
16           _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE
17               || _POSIX_C_SOURCE >= 200112L
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DESCRIPTION

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

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

45       POSIX.1-2001, POSIX.1-2008, C99.
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NOTES

48       Wide-character output to  a  byte  oriented  stream  can  be  performed
49       through the fprintf(3) function with the %lc and %ls directives.
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51       Char  oriented  output  to a wide-character oriented stream can be per‐
52       formed through the fwprintf(3) function with the %c and %s directives.
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SEE ALSO

55       fprintf(3), fwprintf(3)
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COLOPHON

58       This page is part of release 5.13 of the Linux  man-pages  project.   A
59       description  of  the project, information about reporting bugs, and the
60       latest    version    of    this    page,    can     be     found     at
61       https://www.kernel.org/doc/man-pages/.
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65GNU                               2021-03-22                          FWIDE(3)
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