nant's projects / dragonfly.git / blame
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1 | .\" Copyright (c) 1990, 1991, 1993 |
| 2 | .\" The Regents of the University of California. All rights reserved. | |
| 3 | .\" | |
| 4 | .\" This code is derived from software contributed to Berkeley by | |
| 5 | .\" Chris Torek and the American National Standards Committee X3, | |
| 6 | .\" on Information Processing Systems. | |
| 7 | .\" | |
| 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. | |
| dc71b7ab | 16 | .\" 3. Neither the name of the University nor the names of its contributors |
| 984263bc MD |
17 | .\" may be used to endorse or promote products derived from this software |
| 18 | .\" without specific prior written permission. | |
| 19 | .\" | |
| 20 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
| 21 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 22 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 23 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
| 24 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| 25 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
| 26 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
| 27 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 28 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
| 29 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| 30 | .\" SUCH DAMAGE. | |
| 31 | .\" | |
| 32 | .\" @(#)ungetc.3 8.1 (Berkeley) 6/4/93 | |
| e0f95098 | 33 | .\" $FreeBSD: src/lib/libc/stdio/ungetc.3,v 1.14 2007/01/09 00:28:07 imp Exp $ |
| 1de703da | 34 | .\" $DragonFly: src/lib/libc/stdio/ungetc.3,v 1.2 2003/06/17 04:26:46 dillon Exp $ |
| 984263bc MD |
35 | .\" |
| 36 | .Dd June 4, 1993 | |
| 37 | .Dt UNGETC 3 | |
| 38 | .Os | |
| 39 | .Sh NAME | |
| 40 | .Nm ungetc | |
| 41 | .Nd un-get character from input stream | |
| 42 | .Sh LIBRARY | |
| 43 | .Lb libc | |
| 44 | .Sh SYNOPSIS | |
| 45 | .In 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-back characters will be returned by subsequent reads on the | |
| 57 | stream (in reverse order). | |
| 58 | A successful intervening call, | |
| 59 | using the same stream, | |
| 60 | to one of the file positioning functions | |
| 61 | .Xr ( fseek 3 , | |
| 62 | .Xr fsetpos 3 , | |
| 63 | or | |
| 64 | .Xr rewind 3 ) | |
| 65 | will discard the pushed back characters. | |
| 66 | .Pp | |
| 67 | One character of push-back is guaranteed, | |
| 68 | but as long as there is sufficient memory, | |
| 69 | an effectively infinite amount of pushback is allowed. | |
| 70 | .Pp | |
| 71 | If a character is successfully pushed-back, | |
| 72 | the end-of-file indicator for the stream is cleared. | |
| e0f95098 PA |
73 | The file-position indicator is decremented |
| 74 | by each successful call to | |
| 75 | .Fn ungetc ; | |
| 76 | if its value was 0 before a call, its value is unspecified after | |
| 77 | the call. | |
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78 | .Sh RETURN VALUES |
| 79 | The | |
| 80 | .Fn ungetc | |
| 81 | function returns the character pushed-back after the conversion, | |
| 82 | or | |
| 83 | .Dv EOF | |
| 84 | if the operation fails. | |
| 85 | If the value of the argument | |
| 86 | .Fa c | |
| 87 | character equals | |
| 88 | .Dv EOF , | |
| 89 | the operation will fail and the stream will remain unchanged. | |
| 90 | .Sh SEE ALSO | |
| 91 | .Xr fseek 3 , | |
| 92 | .Xr getc 3 , | |
| e0f95098 PA |
93 | .Xr setvbuf 3 , |
| 94 | .Xr ungetwc 3 | |
| 984263bc MD |
95 | .Sh STANDARDS |
| 96 | The | |
| 97 | .Fn ungetc | |
| 98 | function conforms to | |
| 99 | .St -isoC . |