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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.1‐2008 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.1‐2008, <stdio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .