FFS(3) BSD Library Functions Manual FFS(3)
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.
BSD
April 28, 2010 BSD
