ffs
—
find first bit set in a bit string
Standard C Library (libc, -lc)
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.
The ffs
() function conforms to IEEE Std
1003.1-2001 (“POSIX.1”).
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.