x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
FFS(3) Linux Programmer's Manual FFS(3)
NAME
ffs, ffsl, ffsll - find first bit set in a word
SYNOPSIS
#include <strings.h>
int ffs(int i);
#include <string.h>
int ffsl(long int i);
int ffsll(long long int i);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
ffs():
Since glibc 2.12:
_SVID_SOURCE || _BSD_SOURCE || _POSIX_C_SOURCE >= 200809L ||
_XOPEN_SOURCE >= 700 ||
Before glibc 2.12:
none
ffsl(), ffsll():
_GNU_SOURCE
DESCRIPTION
The ffs() function returns the position of the first (least signifi-
cant) bit set in the word i. The least significant bit is position 1
and the most significant position is, for example, 32 or 64. The func-
tions ffsll() and ffsl() do the same but take arguments of possibly
different size.
RETURN VALUE
These functions return the position of the first bit set, or 0 if no
bits are set in i.
ATTRIBUTES
Multithreading (see pthreads(7))
The ffs(), ffsl(), and ffsll() functions are thread-safe.
CONFORMING TO
ffs(): 4.3BSD, POSIX.1-2001.
The ffsl() and ffsll() functions are glibc extensions.
NOTES
BSD systems have a prototype in <string.h>.
SEE ALSO
memchr(3)
COLOPHON
This page is part of release 3.69 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
http://www.kernel.org/doc/man-pages/.
GNU 2014-04-14 FFS(3)
Want to link to this manual page? Use this URL:
<http://star2.abcm.com/cgi-bin/bsdi-man?query=ffs&sektion=3&manpath=>