NAME

ffs — find first bit set in a bit string

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 rightmost bit. A return value of 0 means that the argument was zero.

SEE ALSO

bit_ffs(3)

STANDARDS

The ffs() function conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

HISTORY

The ffs() function first appeared in 4.2BSD.