FFS(3) | Library Functions Manual | FFS(3)

# NAME

`ffs` — find first bit set in a bit string

# 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 rightmost bit. A return value of 0 means that the argument was zero.

# SEE ALSO

bit_ffs(3)

# STANDARDS

The `ffs`() function conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

# HISTORY

The `ffs`() function first appeared in 4.2BSD.

August 30, 2019 | Debian