ffsll(3) -- Linux man page

 

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. Thefunctionsffsll()andffsl()dothesamebuttake arguments of possibly different size.  

RETURN VALUE

These functions return the position of the first bit set, or 0 if no bits are set.  

CONFORMING TO

BSD 4.3, POSIX 1003.1-2001.  

NOTES

BSD systems have a prototype in <string.h>.