ISFINITE(3P)

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

💖 ISFINITE(3P) — bestie edition 💖

okay so this lil page lives in the POSIX Programmer's Manual (yes, that one, the IEEE/The Open Group one, 2017 edition) and we're gonna read it together. grab a snack. 🍓

✨ PROLOG ✨

so like, real talk first: 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 consult the corresponding Linux manual page for the deets on Linux behavior. or honestly? the interface might not even be implemented on Linux at all. 💀 vibe check your platform first, bestie.

🌸 NAME 🌸

isfinite — test for finite value. that's it. that's the whole job. icon behavior. 👑

🎀 SYNOPSIS 🎀

#include <math.h>

int isfinite(real-floating x);

🦋 DESCRIPTION 🦋

so the functionality described on this reference page is aligned with the ISO C standard. And listen — if there's any conflict between what's written here and the ISO C standard? That is unintentional, no cap. This volume of POSIX.1‐2017 defers to the ISO C standard. ISO C said it first, we're just the messenger. 💅

Now the actual tea: the isfinite() macro shall determine whether its argument has a finite value — and by finite we mean zero, subnormal, or normal, and not infinite or NaN. Got it? zero ✅ subnormal ✅ normal ✅ infinite ❌ NaN ❌.

But wait, there's a lil two-step to it:

  1. First, an argument represented in a format wider than its semantic type is converted to its semantic type.
  2. Then determination is based on the type of the argument.

so it converts first, then judges. it's giving "let me fix my hair before the photo." 📸

⭐ RETURN VALUE ⭐

the isfinite() macro shall return a non-zero value if and only if its argument has a finite value. that's the whole contract. if and only if. no vibes-based ambiguity here, this is a strict situationship. 🫶

💀 ERRORS 💀

No errors are defined. literally none. it's unbothered. ✨

heads up bestie: the following sections are informative — meaning they're the fun commentary track, not the binding requirements.

🙈 EXAMPLES 🙈

None. (yes really. the page said "no thoughts, head empty." 😭)

💜 APPLICATION USAGE 💜

None. (still nothing. we're thriving in the void.) 🌈

🧚 RATIONALE 🧚

None. (the reasoning? immaculate but unlisted. iykyk.) ✨

🔥 FUTURE DIRECTIONS 🔥

None. (the future is unwritten and also blank.) 🌟

👑 SEE ALSO 👑

  • fpclassify()
  • isinf()
  • isnan()
  • isnormal()
  • signbit()

also, the Base Definitions volume of POSIX.1‐2017, specifically <math.h>. go read that if you want the whole lore. 📚

okay legal moment, pay attention:

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.

And like, 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!! 🎀 this dropped from IEEE/The Open Group in 2017 — sending you off with love and a finite, non-NaN vibe. mwah 💋✨

📦 where this page comes from