NAME
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 VALUES
The rewind function returns no value. Upon successful com-
pletion, fgetpos, fseek, fsetpos return 0, and ftell returns
the current offset. Otherwise, -1 is returned and the glo-
bal variable 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 function 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).
SEE ALSO
lseek(2)
STANDARDS
The fgetpos, fsetpos, fseek, ftell, and rewind functions
conform to ANSI C3.159-1989 (``ANSI C'').