|
FFS(3) |
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.
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.
