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FFS(3P) POSIX Programmer's Manual FFS(3P)
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.
ffs — find first set bit
#include <strings.h>
int ffs(int i);
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).
The ffs() function shall return the index of the first bit set. If i
is 0, then ffs() shall return 0.
No errors are defined.
The following sections are informative.
None.
None.
None.
None.
The Base Definitions volume of POSIX.1‐2008, strings.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 FFS(3P)
Pages that refer to this page: strings.h(0p)