1FWIDE(3P)                  POSIX Programmer's Manual                 FWIDE(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       fwide — set stream orientation
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SYNOPSIS

15       #include <stdio.h>
16       #include <wchar.h>
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18       int fwide(FILE *stream, int mode);
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DESCRIPTION

21       The functionality described on this reference page is aligned with  the
22       ISO C  standard.  Any  conflict between the requirements described here
23       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2017
24       defers to the ISO C standard.
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26       The  fwide()  function  shall  determine  the orientation of the stream
27       pointed to by stream.  If mode is greater than zero, the function first
28       attempts  to  make the stream wide-oriented. If mode is less than zero,
29       the function first attempts to make the  stream  byte-oriented.  Other‐
30       wise,  mode  is zero and the function does not alter the orientation of
31       the stream.
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33       If the orientation of the stream has already been  determined,  fwide()
34       shall not change it.
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36       The  fwide() function shall not change the setting of errno if success‐
37       ful.
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39       Since no return value is reserved to indicate an error, an  application
40       wishing  to check for error situations should set errno to 0, then call
41       fwide(), then check errno, and if it is non-zero, assume an  error  has
42       occurred.
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RETURN VALUE

45       The  fwide()  function shall return a value greater than zero if, after
46       the call, the stream has wide-orientation, a value less  than  zero  if
47       the  stream has byte-orientation, or zero if the stream has no orienta‐
48       tion.
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ERRORS

51       The fwide() function may fail if:
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53       EBADF  The stream argument is not a valid stream.
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55       The following sections are informative.
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EXAMPLES

58       None.
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APPLICATION USAGE

61       A call to fwide() with mode set to zero can be used  to  determine  the
62       current orientation of a stream.
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RATIONALE

65       None.
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FUTURE DIRECTIONS

68       None.
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SEE ALSO

71       The Base Definitions volume of POSIX.1‐2017, <stdio.h>, <wchar.h>
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74       Portions  of  this text are reprinted and reproduced in electronic form
75       from IEEE Std 1003.1-2017, Standard for Information Technology --  Por‐
76       table  Operating System Interface (POSIX), The Open Group Base Specifi‐
77       cations Issue 7, 2018 Edition, Copyright (C) 2018 by the  Institute  of
78       Electrical  and  Electronics Engineers, Inc and The Open Group.  In the
79       event of any discrepancy between this version and the original IEEE and
80       The  Open Group Standard, the original IEEE and The Open Group Standard
81       is the referee document. The original Standard can be  obtained  online
82       at http://www.opengroup.org/unix/online.html .
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84       Any  typographical  or  formatting  errors that appear in this page are
85       most likely to have been introduced during the conversion of the source
86       files  to  man page format. To report such errors, see https://www.ker‐
87       nel.org/doc/man-pages/reporting_bugs.html .
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91IEEE/The Open Group                  2017                            FWIDE(3P)
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