NAME
ffs —
find first bit set in a bit
string
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <strings.h>
int
ffs(
int
value);
DESCRIPTION
The
ffs() function finds the first bit set in
value and returns the index of that bit. Bits are
numbered starting from 1, starting at the right-most bit. A return value of 0
means that the argument was zero.
SEE ALSO
bitstring(3),
ffs32(3),
popcount(3)
STANDARDS
The
ffs() function conforms to
IEEE Std
1003.1-2001 (“POSIX.1”).
HISTORY
The
ffs() function appeared in
4.3BSD.
The prototype for it existed previously in the
<string.h> header before it was
moved to
<strings.h> for POSIX
compliance.