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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | SEE ALSO | COLOPHON |
FSEEK(3) Linux Programmer's Manual FSEEK(3)
fgetpos, fseek, fsetpos, ftell, rewind - reposition a stream
#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, const fpos_t *pos);
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.
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.
EBADF The stream specified is not a seekable stream.
EINVAL The whence argument to fseek() was not SEEK_SET, SEEK_END, or
SEEK_CUR. Or: the resulting file offset would be negative.
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).
For an explanation of the terms used in this section, see
attributes(7).
┌────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├────────────────────────────┼───────────────┼─────────┤
│fseek(), ftell(), rewind(), │ Thread safety │ MT-Safe │
│fgetpos(), fsetpos() │ │ │
└────────────────────────────┴───────────────┴─────────┘
POSIX.1-2001, POSIX.1-2008, C89, C99.
lseek(2), fseeko(3)
This page is part of release 4.12 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
GNU 2015-08-08 FSEEK(3)
Pages that refer to this page: lseek(2), fgetc(3), fmemopen(3), fopen(3), fopencookie(3), fseeko(3), gets(3), open_memstream(3), puts(3), feature_test_macros(7)