stdio/FreeBSD/ungetwc.3

   1 .\"     $NetBSD: ungetwc.3,v 1.3 2002/02/07 07:00:27 ross Exp $
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  34 .\"     @(#)ungetc.3    8.1 (Berkeley) 6/4/93
  35 .\" $FreeBSD: src/lib/libc/stdio/ungetwc.3,v 1.6 2007/01/09 00:28:07 imp Exp $
  36 .\"
  37 .Dd March 3, 2004
  38 .Dt UNGETWC 3
  39 .Os
  40 .Sh NAME
  41 .Nm ungetwc
  42 .Nd un-get wide character from input stream
  43 .Sh LIBRARY
  44 .Lb libc
  45 .Sh SYNOPSIS
  46 .In stdio.h
  47 .In wchar.h
  48 .Ft wint_t
  49 .Fn ungetwc "wint_t wc" "FILE *stream"
  50 .Sh DESCRIPTION
  51 The
  52 .Fn ungetwc
  53 function pushes the wide character
  54 .Fa wc
  55 (converted to an
  56 .Vt wchar_t )
  57 back onto the input stream pointed to by
  58 .Fa stream .
  59 The pushed-backed wide characters will be returned by subsequent reads on the
  60 stream (in reverse order).
  61 A successful intervening call, using the same stream, to one of the file
  62 positioning functions
  63 .Xr fseek 3 ,
  64 .Xr fsetpos 3 ,
  65 or
  66 .Xr rewind 3
  67 will discard the pushed back wide characters.
  68 .Pp
  69 One wide character of push-back is guaranteed,
  70 but as long as there is
  71 sufficient memory, an effectively infinite amount of pushback is allowed.
  72 .Pp
  73 If a character is successfully pushed-back,
  74 the end-of-file indicator for the stream is cleared.
  75 .Sh RETURN VALUES
  76 The
  77 .Fn ungetwc
  78 function
  79 returns
  80 the wide character pushed-back after the conversion, or
  81 .Dv WEOF
  82 if the operation fails.
  83 If the value of the argument
  84 .Fa c
  85 character equals
  86 .Dv WEOF ,
  87 the operation will fail and the stream will remain unchanged.
  88 .Sh SEE ALSO
  89 .Xr fseek 3 ,
  90 .Xr getwc 3
  91 .Sh STANDARDS
  92 The
  93 .Fn ungetwc
  94 function conforms to
  95 .St -isoC-99 .