NAME

ffs - find first bit set in a word

SYNOPSIS

#include <strings.h>

int ffs(int i);

#define _GNU_SOURCE

#include <string.h>

int ffsl(long int i);

int ffsll(long long int i);

DESCRIPTION

The ffs() function returns the position of the first (least significant) bit set in the word i. The least significant bit is position 1 and the most significant position e.g. 32 or 64. The functions 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 <string.h>.

SEE ALSO

feature_test_macros(7)