FTELL(P) POSIX Programmer's Manual FTELL(P)
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-position indicator for the
stream pointed to by stream.
The ftello() function shall be equivalent to ftell(), except that the return value is of
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 descriptor.
For ftell(), the current file offset cannot be represented correctly in an object
of type long.
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 or FIFO.
The ftell() function may fail if:
ESPIPE The file descriptor underlying stream is associated with a socket.
The following sections are informative.
fgetpos() , 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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 FTELL(P)