1FWIDE(3) Linux Programmer's Manual FWIDE(3)
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6 fwide - set and determine the orientation of a FILE stream
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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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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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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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45 POSIX.1-2001, POSIX.1-2008, C99.
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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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55 fprintf(3), fwprintf(3)
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58 This page is part of release 5.10 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 2016-03-15 FWIDE(3)