FTELLO64(3)

NAME
5.3 `ftello64'--return position in a stream or file

SYNOPSIS
     #include <stdio.h>
     _off64_t ftello64(FILE *FP);
     _off64_t _ftello64_r(struct _reent *PTR, FILE *FP);

DESCRIPTION
Objects of type `FILE' can have a "position" that records how much of the file your program has already read. Many of the `stdio' functions depend on this position, and many change it as a side effect.
   The result of `ftello64' is the current position for a large file identified by FP. If you record this result, you can later use it with `fseeko64' to return the file to this position. The difference between `ftello' and `ftello64' is that `ftello' returns `off_t' and `ftello64' is designed to work for large files (>2GB) and returns `_off64_t'.
   In the current implementation, `ftello64' simply uses a character count to represent the file position; this is the same number that would be recorded by `fgetpos64'.
   The function exists only if the __LARGE64_FILES flag is defined. An error occurs if the FP was not opened via `fopen64'.

RETURNS
`ftello64' returns the file position, if possible. If it cannot do this, it returns `-1'. Failure occurs on streams that do not support positioning or not opened via `fopen64'; the global `errno' indicates this condition with the value `ESPIPE'.

PORTABILITY
`ftello64' is a glibc extension.
   No supporting OS subroutines are required.

SEE ALSO
ftello64 is part of the library. The full documentation for is maintained as a Texinfo manual. If info and are properly installed at your site, the command

    info

will give you access to the complete manual.