fgetpos, fseek, fsetpos, ftell, rewind — reposition
a stream
Synopsis
#include <stdio.h>
int
fseek(
FILE *
stream,
long
offset,
int
whence);
long
ftell(
FILE *
stream);
void
rewind(
FILE *
stream);
int
fgetpos(
FILE *
stream,
fpos_t *
pos);
int
fsetpos(
FILE *
stream,
fpos_t *
pos);
DESCRIPTION
The fseek() function sets
the file position indicator for the stream pointed to by
stream. The new
position, measured in bytes, is obtained by adding offset bytes to the position
specified by whence.
If whence is set to
SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to the
start of the file, the current position indicator, or
end-of-file, respectively. A successful call to the
fseek() function clears the
end-of-file indicator for the stream and undoes any effects
of the ungetc(3) function on the
same stream.
The ftell() function obtains
the current value of the file position indicator for the
stream pointed to by stream.
The rewind() function sets
the file position indicator for the stream pointed to by
stream to the
beginning of the file. It is equivalent to:
(void) fseek(stream, 0L, SEEK_SET)
except that the error indicator for the stream is also
cleared (see clearerr(3)).
The fgetpos() and
fsetpos() functions are
alternate interfaces equivalent to ftell() and fseek() (with whence set to SEEK_SET), setting and storing the current
value of the file offset into or from the object referenced
by pos. On some
non-UNIX systems an fpos_t object may be a
complex object and these routines may be the only way to
portably reposition a text stream.
RETURN VALUE
The rewind() function
returns no value. Upon successful completion, fgetpos(), fseek(), fsetpos() return 0, and ftell() returns the current offset.
Otherwise, −1 is returned and errno is set to indicate the error.
ERRORS
EBADF
The stream
specified is not a seekable stream.
EINVAL
The whence
argument to fseek() was
not SEEK_SET,
SEEK_END, or SEEK_CUR.
The functions fgetpos(),
fseek(), fsetpos(), and ftell() may also fail and set errno for any of the errors specified for
the routines fflush(3), fstat(2), lseek(2), and malloc(3).
Copyright (c) 1990, 1991 The Regents of the University of California.
All rights reserved.
This code is derived from software contributed to Berkeley by
Chris Torek and the American National Standards Committee X3,
on Information Processing Systems.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this software
must display the following acknowledgement:
This product includes software developed by the University of
California, Berkeley and its contributors.
4. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
@(#)fseek.3
6.11 (Berkeley) 6/29/91
Converted for Linux, Mon Nov 29 15:22:01 1993, faith@cs.unc.edu
