FFS(P) POSIX Programmer s Manual FFS(P)
PROLOG This manual page is part of the POSIX Programmer s Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAME ffs - find first set bit
SYNOPSIS #include <strings.h>
int ffs(int i);
DESCRIPTION The ffs() function shall find the first bit set (beginning with the least significant bit) in i, and return the index of that bit. Bits are numbered starting at one (the least significant bit).
RETURN VALUE The ffs() function shall return the index of the first bit set. If i is 0, then ffs() shall return 0.
ERRORS No errors are defined.
The following sections are informative.
APPLICATION USAGE None.
FUTURE DIRECTIONS None.
SEE ALSO The Base Definitions volume of IEEE Std 1003.1-2001, <strings.h>
COPYRIGHT Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 FFS(P)