FTELL
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Page Index
PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
NAME
ftell,
ftello
--- return a file offset in a stream
SYNOPSIS
#include <stdio.h>
long ftell(FILE *stream);
off_t ftello(FILE *stream);
DESCRIPTION
The functionality described on this reference page is aligned with the
ISO C standard. Any conflict between the requirements described here and the
ISO C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO C standard.
The
ftell()
function shall obtain the current value of the file-position indicator
for the stream pointed to by
stream.
The
ftell()
function shall not change the setting of
errno
if successful.
The
ftello()
function shall be equivalent to
ftell(),
except that the return value is of type
off_t
and the
ftello()
function may change the setting of
errno
if successful.
RETURN VALUE
Upon successful completion,
ftell()
and
ftello()
shall return the current value of the file-position indicator for the
stream measured in bytes from the beginning of the file.
Otherwise,
ftell()
and
ftello()
shall return -1, and set
errno
to indicate the error.
ERRORS
The
ftell()
and
ftello()
functions shall fail if:
- EBADF
-
The file descriptor underlying
stream
is not an open file descriptor.
- EOVERFLOW
-
For
ftell(),
the current file offset cannot be represented correctly in an object of
type
long.
- EOVERFLOW
-
For
ftello(),
the current file offset cannot be represented correctly in an object of
type
off_t.
- ESPIPE
-
The file descriptor underlying
stream
is associated with a pipe, FIFO, or socket.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
Section 2.5,
Standard I/O Streams,
fgetpos(),
fopen(),
fseek(),
lseek()
The Base Definitions volume of POSIX.1-2017,
<stdio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .