fseeko(3) — Linux manual page

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)

COLOPHON

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

Pages that refer to this page: fseek(3), off_t(3type), open_memstream(3), feature_test_macros(7)

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