fseeko, ftello - seek to or report file position

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                                                                   │ Attribute     │ Value   │
       ├─────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │ fseeko(), ftello()                                                          │ Thread safety │ MT-Safe │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

       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 return 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.

       See the ERRORS in fseek(3).

       glibc 2.1.  POSIX.1-2001, SUSv2.

       Standard C library (libc, -lc)

       fseeko, ftello - seek to or report file position

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

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

fseek(3)

Linux man-pages 6.9.1                              2024-05-02                                          fseeko(3)

       POSIX.1-2008.

#include<stdio.h>intfseeko(FILE*stream,off_toffset,intwhence);off_tftello(FILE*stream);

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

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