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FFS(3)                 FreeBSD Library Functions Manual                 FFS(3)

NAME
     ffs, ffsl, ffsll, fls, flsl, flsll - find first or last bit set in a bit
     string

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <strings.h>

     int
     ffs(int value);

     int
     ffsl(long value);

     int

     int
     ffsll(long long value);

     fls(int value);

     int
     flsl(long value);

     int
     flsll(long long value);

DESCRIPTION
     The ffs(), ffsl() and ffsll() functions find the first bit set (beginning
     with the least significant bit) in value and return the index of that
     bit.

     The fls(), flsl() and flsll() functions find the last bit set in value
     and return the index of that bit.

     Bits are numbered starting at 1 (the least significant bit).  A return
     value of zero from any of these functions means that the argument was
     zero.

SEE ALSO
     bitstring(3)

HISTORY
     The ffs() function appeared in 4.3BSD.  Its prototype existed previously
     in <string.h> before it was moved to <strings.h> for IEEE Std 1003.1-2001
     (``POSIX.1'') compliance.

     The ffsl(), fls() and flsl() functions appeared in FreeBSD 5.3.  The
     ffsll() and flsll() functions appeared in FreeBSD 7.1.

FreeBSD 11.0-PRERELEASE        October 26, 2008        FreeBSD 11.0-PRERELEASE

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY

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