xref: /minix3/lib/libc/stdio/ungetwc.3 (revision 2fe8fb192fe7e8720e3e7a77f928da545e872a6a)
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6*2fe8fb19SBen Gras.\" This code is derived from software contributed to Berkeley by
7*2fe8fb19SBen Gras.\" Chris Torek and the American National Standards Committee X3,
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34*2fe8fb19SBen Gras.\"     @(#)ungetc.3	8.1 (Berkeley) 6/4/93
35*2fe8fb19SBen Gras.\"
36*2fe8fb19SBen Gras.Dd October 24, 2001
37*2fe8fb19SBen Gras.Dt UNGETWC 3
38*2fe8fb19SBen Gras.Os
39*2fe8fb19SBen Gras.Sh NAME
40*2fe8fb19SBen Gras.Nm ungetwc
41*2fe8fb19SBen Gras.Nd un-get wide character from input stream
42*2fe8fb19SBen Gras.Sh LIBRARY
43*2fe8fb19SBen Gras.Lb libc
44*2fe8fb19SBen Gras.Sh SYNOPSIS
45*2fe8fb19SBen Gras.In stdio.h
46*2fe8fb19SBen Gras.In wchar.h
47*2fe8fb19SBen Gras.Ft wint_t
48*2fe8fb19SBen Gras.Fn ungetwc "wint_t wc" "FILE *stream"
49*2fe8fb19SBen Gras.Sh DESCRIPTION
50*2fe8fb19SBen GrasThe
51*2fe8fb19SBen Gras.Fn ungetwc
52*2fe8fb19SBen Grasfunction pushes the wide character
53*2fe8fb19SBen Gras.Fa wc
54*2fe8fb19SBen Gras(converted to an wchar_t)
55*2fe8fb19SBen Grasback onto the input stream pointed to by
56*2fe8fb19SBen Gras.Fa stream .
57*2fe8fb19SBen GrasThe pushed-backed wide characters will be returned by subsequent reads on the
58*2fe8fb19SBen Grasstream (in reverse order).
59*2fe8fb19SBen GrasA successful intervening call, using the same stream, to one of the file
60*2fe8fb19SBen Graspositioning functions
61*2fe8fb19SBen Gras.Xr fseek 3 ,
62*2fe8fb19SBen Gras.Xr fsetpos 3 ,
63*2fe8fb19SBen Grasor
64*2fe8fb19SBen Gras.Xr rewind 3
65*2fe8fb19SBen Graswill discard the pushed back wide characters.
66*2fe8fb19SBen Gras.Pp
67*2fe8fb19SBen GrasOne wide character of push-back is guaranteed,
68*2fe8fb19SBen Grasbut as long as there is
69*2fe8fb19SBen Grassufficient memory, an effectively infinite amount of pushback is allowed.
70*2fe8fb19SBen Gras.Pp
71*2fe8fb19SBen GrasIf a character is successfully pushed-back,
72*2fe8fb19SBen Grasthe end-of-file indicator for the stream is cleared.
73*2fe8fb19SBen Gras.Sh RETURN VALUES
74*2fe8fb19SBen GrasThe
75*2fe8fb19SBen Gras.Fn ungetwc
76*2fe8fb19SBen Grasfunction
77*2fe8fb19SBen Grasreturns
78*2fe8fb19SBen Grasthe wide character pushed-back after the conversion, or
79*2fe8fb19SBen Gras.Dv WEOF
80*2fe8fb19SBen Grasif the operation fails.
81*2fe8fb19SBen GrasIf the value of the argument
82*2fe8fb19SBen Gras.Fa c
83*2fe8fb19SBen Grascharacter equals
84*2fe8fb19SBen Gras.Dv WEOF ,
85*2fe8fb19SBen Grasthe operation will fail and the stream will remain unchanged.
86*2fe8fb19SBen Gras.Sh SEE ALSO
87*2fe8fb19SBen Gras.Xr fseek 3 ,
88*2fe8fb19SBen Gras.Xr getwc 3
89*2fe8fb19SBen Gras.Sh STANDARDS
90*2fe8fb19SBen GrasThe
91*2fe8fb19SBen Gras.Fn ungetwc
92*2fe8fb19SBen Grasfunction conforms to
93*2fe8fb19SBen Gras.St -isoC-99 .
94*2fe8fb19SBen Gras.Sh BUGS
95*2fe8fb19SBen GrasThe current implementation uses a fixed sized ungetwc-buffer.
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