FSEEK(3) | Library Functions Manual | FSEEK(3) |
fgetpos
, fseek
,
fseeko
, fsetpos
,
ftell
, ftello
,
rewind
—
#include <stdio.h>
int
fseek
(FILE
*stream, long int
offset, int
whence);
int
fseeko
(FILE
*stream, off_t
offset, int
whence);
long int
ftell
(FILE
*stream);
off_t
ftello
(FILE
*stream);
void
rewind
(FILE
*stream);
int
fgetpos
(FILE
* restrict stream, fpos_t
* restrict pos);
int
fsetpos
(FILE
* restrict stream, const
fpos_t * restrict pos);
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 fseeko
() function is identical to the
fseek
() function except that the
offset argument is of type
off_t.
The ftell
() function obtains the current
value of the file position indicator for the stream pointed to by
stream.
The ftello
() function is identical to the
ftell
() function except that the return value is of
type off_t.
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)).
In this implementations,
“fpos_t” is a complex object that
represents both the position and the parse state of the stream, making these
routines as the only way to portably reposition a text stream. The
pos argument of fsetpos
() must
always be initialized by a call to fgetpos
().
rewind
() function returns no value.
Upon successful completion, fgetpos
(),
fseek
(), fseeko
(), and
fsetpos
() return 0, whereas the functions
ftell
() and ftello
() return
the current offset. On failure, fseek
(),
fseeko
(), ftell
(), and
ftello
() return -1, while
fgetpos
() and fsetpos
()
return a nonzero value.
On error all functions set the global variable
errno to indicate the error. Since the
rewind
() function does not return an error code,
applications need to clear errno before calling it in
order to detect errors.
EBADF
]EINVAL
]fseek
() was not SEEK_SET
,
SEEK_END
, or
SEEK_CUR
.EOVERFLOW
]ftell
(), the current file offset cannot be
represented correctly in an object of type
long.The function fgetpos
(),
fseek
(), fseeko
(),
fsetpos
(), ftell
(),
ftello
(), and rewind
() may
also fail and set errno for any of the errors
specified for the routines
fflush(3),
fstat(2),
lseek(2), and
malloc(3).
fgetpos
(), fsetpos
(),
fseek
(), ftell
(), and
rewind
() functions conform to ANSI
X3.159-1989 (“ANSI C89”). The
fseeko
() and ftello
()
functions conform to X/Open System Interfaces and Headers
Issue 5 (“XSH5”).
fgetpos
() and fsetpos
()
functions don't store/set shift states of the stream in this implementation.
January 1, 2017 | NetBSD 9.2 |