FTELL(3P) POSIX Programmer's Manual FTELL(3P)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.
ftell, ftello - return a file offset in a stream
long ftell(FILE *stream);
off_t ftello(FILE *stream);
The ftell() function shall obtain the current value of the file-posi‐
tion indicator for the stream pointed to by stream.
The ftello() function shall be equivalent to ftell(), except that the
return value is of type off_t.
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, cast to long and
off_t respectively, and set errno to indicate the error.
The ftell() and ftello() functions shall fail if:
EBADF The file descriptor underlying stream is not an open file
For ftell(), the current file offset cannot be represented cor‐
rectly in an object of type long.
For ftello(), the current file offset cannot be represented cor‐
rectly in an object of type off_t.
ESPIPE The file descriptor underlying stream is associated with a pipe
The ftell() function may fail if:
ESPIPE The file descriptor underlying stream is associated with a
The following sections are informative.
SEE ALSOfgetpos(), fopen(), fseek(), lseek(), the Base Definitions volume of
IEEE Std 1003.1-2001, <stdio.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .
IEEE/The Open Group 2003 FTELL(3P)