mirror of https://github.com/mkerrisk/man-pages
89 lines
2.5 KiB
Groff
89 lines
2.5 KiB
Groff
.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
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.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" References consulted:
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.\" GNU glibc-2 source code and manual
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.\" Dinkumware C library reference http://www.dinkumware.com/
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.\" OpenGroup's Single Unix specification http://www.UNIX-systems.org/online.html
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.\" ISO/IEC 9899:1999
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.\"
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.TH FWIDE 3 2007-07-26 "GNU" "Linux Programmer's Manual"
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.SH NAME
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fwide \- set and determine the orientation of a FILE stream
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.SH SYNOPSIS
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.nf
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.B #include <wchar.h>
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.sp
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.BI "int fwide(FILE *" stream ", int " mode );
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.fi
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.BR fwide ():
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_XOPEN_SOURCE\ >=\ 500 || _ISOC99_SOURCE; or
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.I cc\ -std=c99
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.SH DESCRIPTION
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When \fImode\fP is zero, the
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.BR fwide ()
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function determines the current
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orientation of \fIstream\fP.
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It returns a value > 0 if \fIstream\fP is
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wide-character oriented, that is, if wide-character I/O is permitted but char
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I/O is disallowed.
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It returns a value < 0 if \fIstream\fP is byte oriented,
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i.e. if char I/O is permitted but wide-character I/O is disallowed.
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It
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returns zero if \fIstream\fP has no orientation yet; in this case the next
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I/O operation might change the orientation (to byte oriented if it is a char
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I/O operation, or to wide-character oriented if it is a wide-character I/O
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operation).
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.PP
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Once a stream has an orientation, it cannot be changed and persists until
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the stream is closed.
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.PP
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When \fImode\fP is nonzero, the
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.BR fwide ()
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function first attempts to set
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\fIstream\fP's orientation (to wide-character oriented if \fImode\fP > 0, or
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to byte oriented if \fImode\fP < 0).
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It then returns a value denoting the
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current orientation, as above.
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.SH "RETURN VALUE"
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The
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.BR fwide ()
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function returns the stream's orientation, after possibly
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changing it.
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A return value > 0 means wide-character oriented.
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A return value
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< 0 means byte oriented.
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A return value of zero means undecided.
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.SH "CONFORMING TO"
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C99, POSIX.1-2001.
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.SH NOTES
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Wide-character output to a byte oriented stream can be performed through the
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.BR fprintf (3)
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function with the
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.B %lc
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and
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.B %ls
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directives.
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.PP
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Char oriented output to a wide-character oriented stream can be performed
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through the
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.BR fwprintf (3)
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function with the
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.B %c
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and
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.B %s
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directives.
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.SH "SEE ALSO"
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.BR fprintf (3),
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.BR fwprintf (3)
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