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af359dea | 1 | .\" Copyright (c) 1990, 1991 The Regents of the University of California. |
c9be6cfe | 2 | .\" All rights reserved. |
1f4480e5 | 3 | .\" |
c9be6cfe | 4 | .\" This code is derived from software contributed to Berkeley by |
af359dea C |
5 | .\" Chris Torek and the American National Standards Committee X3, |
6 | .\" on Information Processing Systems. | |
c9be6cfe | 7 | .\" |
c0567266 KB |
8 | .\" Redistribution and use in source and binary forms, with or without |
9 | .\" modification, are permitted provided that the following conditions | |
10 | .\" are met: | |
11 | .\" 1. Redistributions of source code must retain the above copyright | |
12 | .\" notice, this list of conditions and the following disclaimer. | |
13 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
14 | .\" notice, this list of conditions and the following disclaimer in the | |
15 | .\" documentation and/or other materials provided with the distribution. | |
16 | .\" 3. All advertising materials mentioning features or use of this software | |
17 | .\" must display the following acknowledgement: | |
18 | .\" This product includes software developed by the University of | |
19 | .\" California, Berkeley and its contributors. | |
20 | .\" 4. Neither the name of the University nor the names of its contributors | |
21 | .\" may be used to endorse or promote products derived from this software | |
22 | .\" without specific prior written permission. | |
23 | .\" | |
24 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
25 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
26 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
27 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
28 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
29 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
30 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
31 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
32 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
33 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
34 | .\" SUCH DAMAGE. | |
c9be6cfe | 35 | .\" |
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36 | .\" @(#)ungetc.3 6.6 (Berkeley) 6/29/91 |
37 | .\" | |
38 | .Dd June 29, 1991 | |
39 | .Dt UNGETC 3 | |
40 | .Os | |
41 | .Sh NAME | |
42 | .Nm ungetc | |
43 | .Nd un-get character from input stream | |
44 | .Sh SYNOPSIS | |
45 | .Fd #include <stdio.h> | |
46 | .Ft int | |
47 | .Fn ungetc "int c" "FILE *stream" | |
48 | .Sh DESCRIPTION | |
49 | The | |
50 | .Fn ungetc | |
51 | function pushes the character | |
52 | .Fa c | |
53 | (converted to an unsigned char) | |
54 | back onto the input stream pointed to by | |
55 | .Fa stream . | |
56 | The pushed-backed characters will be returned by subsequent reads on the | |
57 | stream (in reverse order). | |
58 | A successful intervening call, using the same stream, to one of the file | |
59 | positioning functions | |
60 | .Po | |
61 | .Xr fseek 3 , | |
62 | .Xr fsetpos 3 , | |
63 | or | |
64 | .Xr rewind 3 | |
65 | .Pc | |
66 | will discard the pushed back characters. | |
67 | .Pp | |
68 | One character of push-back is guaranteed, | |
69 | but as long as there is | |
c9be6cfe | 70 | sufficient memory, an effectively infinite amount of pushback is allowed. |
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71 | .Pp |
72 | If a character is successfully pushed-back, | |
73 | the end-of-file indicator for the stream is cleared. | |
74 | .Sh RETURN VALUES | |
75 | The | |
76 | .Fn ungetc | |
77 | function | |
1f4480e5 | 78 | returns |
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79 | the character pushed-back after the conversion, or |
80 | .Dv EOF | |
81 | if the operation fails. | |
82 | If the value of the argument | |
83 | .Fa c | |
84 | character equals | |
85 | .Dv EOF , | |
86 | the operation will fail and the stream will remain unchanged. | |
87 | .Sh SEE ALSO | |
88 | .Xr getc 3 , | |
89 | .Xr fseek 3 , | |
90 | .Xr setvbuf 3 | |
91 | .Sh STANDARDS | |
92 | The | |
93 | .Fn ungetc | |
94 | function conforms to | |
95 | .St -ansiC . |