ftello3
Seek to or report file position
Part of fseeko(3).
Usage
#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
Library
Standard C library (libc, -lc)
Overview
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 |
Notes
The declarations of these functions can also be obtained by defining the obsolete _LARGEFILE_SOURCE feature test macro.
Releases
12 releases since Debian 3.1 (Sarge); the text changed 11 times.