1FFS(3P)                    POSIX Programmer's Manual                   FFS(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       ffs — find first set bit
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SYNOPSIS

15       #include <strings.h>
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17       int ffs(int i);
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DESCRIPTION

20       The ffs() function shall find the first bit  set  (beginning  with  the
21       least significant bit) in i, and return the index of that bit. Bits are
22       numbered starting at one (the least significant bit).
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RETURN VALUE

25       The ffs() function shall return the index of the first bit set. If i is
26       0, then ffs() shall return 0.
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ERRORS

29       No errors are defined.
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31       The following sections are informative.
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EXAMPLES

34       None.
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APPLICATION USAGE

37       None.
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RATIONALE

40       None.
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FUTURE DIRECTIONS

43       None.
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SEE ALSO

46       The Base Definitions volume of POSIX.1‐2017, <strings.h>
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49       Portions  of  this text are reprinted and reproduced in electronic form
50       from IEEE Std 1003.1-2017, Standard for Information Technology --  Por‐
51       table  Operating System Interface (POSIX), The Open Group Base Specifi‐
52       cations Issue 7, 2018 Edition, Copyright (C) 2018 by the  Institute  of
53       Electrical  and  Electronics Engineers, Inc and The Open Group.  In the
54       event of any discrepancy between this version and the original IEEE and
55       The  Open Group Standard, the original IEEE and The Open Group Standard
56       is the referee document. The original Standard can be  obtained  online
57       at http://www.opengroup.org/unix/online.html .
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59       Any  typographical  or  formatting  errors that appear in this page are
60       most likely to have been introduced during the conversion of the source
61       files  to  man page format. To report such errors, see https://www.ker‐
62       nel.org/doc/man-pages/reporting_bugs.html .
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66IEEE/The Open Group                  2017                              FFS(3P)
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