FFS(3P)

📦 version 2017a, in alpine 3.22, alpine 3.23, alpine 3.24, arch rolling, nixpkgs unstable, opensuse-leap 16.0

💖 ffs(3P) — the POSIX Programmer's Manual era 💖

okay bestie, welcome to FFS(3P), straight out of the POSIX Programmer's Manual (IEEE/The Open Group, 2017, she's a classic 🎀). pull up a chair, we're finding bits today.

✨ PROLOG ✨

so like, this manual page is part of the POSIX Programmer's Manual. the Linux implementation of this interface may differ — so if you're on Linux, go check the corresponding Linux manual page for the tea on Linux behavior, mkay? or the interface might not even be implemented on Linux at all 💀. no cap, read the fine print.

🌸 NAME 🌸

ffs — find first set bit 🦋 (yes that's literally the whole name, she's simple and she's iconic)

🎀 SYNOPSIS 🎀

#include <strings.h>

int ffs(int i);

there she is. one function. one int. one dream. ✨

💅 DESCRIPTION 💅

so the ffs() function shall find the first bit set (and we start counting from the least significant bit, bestie, don't come at me) in i, and return the index of that bit.

and listen — bits are numbered starting at one. ONE. not zero. the least significant bit is bit number one. so if you were about to zero-index this, stop, that's not the vibe here 🙈.

🔥 RETURN VALUE 🔥

ffs() shall return the index of the first bit set. and if i is 0? then ffs() shall return 0. that's it. that's the deal. zero in, zero out, it's giving balanced. 💖

💀 ERRORS 💀

No errors are defined. she simply does not do errors. no notes. 👑

and just so you know — the following sections are informative. not normative. just vibes.

🌈 EXAMPLES 🌈

None. no examples. she's mysterious like that. iykyk.

🫶 APPLICATION USAGE 🫶

None. nothing to add. she said what she said.

🧚 RATIONALE 🧚

None. no rationale. she just is.

⭐ FUTURE DIRECTIONS ⭐

None. the future is bright and also empty. periodt.

👀 SEE ALSO 👀

  • the Base Definitions volume of POSIX.1‐2017, <strings.h>

okay this part is important, do not skip, put your phone down for a sec 🍓:

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

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 .

and that's the whole page bestie, mwah 💋 this one was brought to you by IEEE/The Open Group, dated 2017, filed under FFS(3P). go find some bits, love u, bye 🦋💖

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