ffs(3) - NetBSD Manual Pages

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FFS(3)                  NetBSD 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.


SEE ALSO

     bitstring(3), ffs32(3), popcount(3)


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 pre-
     viously in the <string.h> header before it was moved to <strings.h> for
     POSIX compliance.

NetBSD 10.1                     April 28, 2010                     NetBSD 10.1