Manpages - ftell.3p

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

  #include <stdio.h>
  long ftell(FILE *stream);
  off_t ftello(FILE *stream);

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.

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.

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.

None.

None.

None.

None.

Section 2.5, Standard I/O Streams, /fgetpos ( )/, /fopen ( )/, /fseek ( )/, /lseek ( )/

The Base Definitions volume of POSIX.1‐2017, <stdio.h>

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 .

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