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FFS(3)                     Linux Programmer's Manual                    FFS(3)



NAME
       ffs, ffsl, ffsll - find first bit set in a word

SYNOPSIS
       #include <&lt;strings.h>&gt;

       int ffs(int i);

       #define _GNU_SOURCE
       #include <&lt;string.h>&gt;

       int ffsl(long int i);

       int ffsll(long long int i);

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.

CONFORMING TO
       4.3BSD, POSIX.1-2001.

NOTES
       BSD systems have a prototype in &lt;string.h&gt;.

SEE ALSO
       feature_test_macros(7)

COLOPHON
       This page is part of release 3.05 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                               2003-08-05                            FFS(3)