The Open Group Base Specifications Issue 7
IEEE Std 1003.1, 2013 Edition
Copyright © 2001-2013 The IEEE and The Open Group

#### NAME

> ffs - find first set bit

#### SYNOPSIS

> ``[XSI] #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.

#### EXAMPLES

> None.

#### APPLICATION USAGE

> None.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> XBD <strings.h>

#### CHANGE HISTORY

> First released in Issue 4, Version 2.

#### Issue 5

> Moved from X/OPEN UNIX extension to BASE.

End of informative text.

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