Synopsis

#include <stdio.h>

long ftell(FILE *stream);

off_t ftello(FILE *stream);

Status

Partially implemented

Conformance

IEEE Std 1003.1-2017

Description

The purpose is to return a file offset in a stream. 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.

Tests

Untested

Known bugs

None

See Also

  1. Standard library functions
  2. Table of Contents