man3/fwide.3

   1 .\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
   2 .\"
   3 .\" This is free documentation; you can redistribute it and/or
   4 .\" modify it under the terms of the GNU General Public License as
   5 .\" published by the Free Software Foundation; either version 2 of
   6 .\" the License, or (at your option) any later version.
   7 .\"
   8 .\" References consulted:
   9 .\"   GNU glibc-2 source code and manual
  10 .\"   Dinkumware C library reference http://www.dinkumware.com/
  11 .\"   OpenGroup's Single Unix specification http://www.UNIX-systems.org/online.html
  12 .\"   ISO/IEC 9899:1999
  13 .\"
  14 .TH FWIDE 3  1999-11-17 "GNU" "Linux Programmer's Manual"
  15 .SH NAME
  16 fwide \- set and determine the orientation of a FILE stream
  17 .SH SYNOPSIS
  18 .nf
  19 .B #include <wchar.h>
  20 .sp
  21 .BI "int fwide(FILE *" stream ", int " mode );
  22 .fi
  23 .SH DESCRIPTION
  24 When \fImode\fP is zero, the \fBfwide\fP() function determines the current
  25 orientation of \fIstream\fP.
  26 It returns a value > 0 if \fIstream\fP is
  27 wide-character oriented, i.e. if wide character I/O is permitted but char
  28 I/O is disallowed.
  29 It returns a value < 0 if \fIstream\fP is byte oriented,
  30 i.e. if char I/O is permitted but wide character I/O is disallowed.
  31 It
  32 returns zero if \fIstream\fP has no orientation yet; in this case the next
  33 I/O operation might change the orientation (to byte oriented if it is a char
  34 I/O operation, or to wide-character oriented if it is a wide character I/O
  35 operation).
  36 .PP
  37 Once a stream has an orientation, it cannot be changed and persists until
  38 the stream is closed.
  39 .PP
  40 When \fImode\fP is non-zero, the \fBfwide\fP() function first attempts to set
  41 \fIstream\fP's orientation (to wide-character oriented if \fImode\fP > 0, or
  42 to byte oriented if \fImode\fP < 0).
  43 It then returns a value denoting the
  44 current orientation, as above.
  45 .SH "RETURN VALUE"
  46 The \fBfwide\fP() function returns the stream's orientation, after possibly
  47 changing it.
  48 A return value > 0 means wide-character oriented.
  49 A return value
  50 < 0 means byte oriented.
  51 A return value of zero means undecided.
  52 .SH "CONFORMING TO"
  53 C99, POSIX.1-2001.
  54 .SH "SEE ALSO"
  55 .BR fprintf (3),
  56 .BR fwprintf (3)
  57 .SH NOTES
  58 Wide-character output to a byte oriented stream can be performed through the
  59 \fBfprintf\fP() function with the %lc and %ls directives.
  60 .PP
  61 Char oriented output to a wide-character oriented stream can be performed
  62 through the \fBfwprintf\fP() function with the %c and %s directives.