fseeko(3)                  Library Functions Manual                  fseeko(3)

NAME
       fseeko, ftello - seek to or report file position

LIBRARY
       Standard C library (libc, -lc)

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 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.

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).

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

       +--------------------------------------------+---------------+---------+
       |Interface                                   | Attribute     | Value   |
       +--------------------------------------------+---------------+---------+
       |fseeko (), ftello ()                        | Thread safety | MT-Safe |
       +--------------------------------------------+---------------+---------+
STANDARDS
       POSIX.1-2008.

HISTORY
       glibc 2.1.  POSIX.1-2001, SUSv2.

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

SEE ALSO
       fseek(3)

Linux man-pages 6.7               2023-10-31                         fseeko(3)