FSEEKO(3)                                                               Linux Programmer's Manual                                                              FSEEKO(3)

NAME
       fseeko, ftello - seek to or report file position

SYNOPSIS
       #include <stdio.h>

       int fseeko(FILE *stream, off_t offset, int whence);
       off_t ftello(FILE *stream);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       fseeko(), ftello():
           _FILE_OFFSET_BITS == 64 || _POSIX_C_SOURCE >= 200112L

DESCRIPTION
       The  fseeko() and ftello() functions are identical to fseek(3) and ftell(3) (see fseek(3)), respectively, except that the offset argument of fseeko() and the re‐
       turn value of ftello() is of type off_t instead of long.

       On some architectures, both off_t and long are 32-bit types, but defining _FILE_OFFSET_BITS with the value 64 (before including any header files) will turn off_t
       into a 64-bit type.

RETURN VALUE
       On successful completion, fseeko() returns 0, while ftello() returns the current offset.  Otherwise, -1 is returned and errno is set to indicate the error.

ERRORS
       See the ERRORS in fseek(3).

VERSIONS
       These functions are available under glibc since version 2.1.

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       ┌──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                                                                                             │ Attribute     │ Value   │
       ├──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │fseeko(), ftello()                                                                                                                    │ Thread safety │ MT-Safe │
       └──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, SUSv2.

NOTES
       The declarations of these functions can also be obtained by defining the obsolete _LARGEFILE_SOURCE feature test macro.

SEE ALSO
       fseek(3)

                                                                               2021-03-22                                                                      FSEEKO(3)