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 defin-
ing _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 in-
dicate the error.
ERRORS
See the ERRORS in fseek(3).
ATTRIBUTES
For an explanation of the terms used in this section, see attrib-
utes(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)
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