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 significant) 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 functions 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.

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 3.44 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

GNU
								    2010-09-20								    FFS(3)