ISWALNUM(3POSIX)

💖 ISWALNUM(3POSIX) 💖

okay bestie, sit down, hydrate, and let me tell you about iswalnum — it's a page from the POSIX Programmer's Manual and it's here to answer one very specific question: is this wide character giving alphanumeric? ✨

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🚨 PROLOG 🚨

so like, real talk first: this manual page is part of the POSIX Programmer's Manual. but heads up bestie 👀 — the Linux implementation of this interface may differ (so pls go consult the corresponding Linux manual page for the deets on Linux behavior), or the interface might not even be implemented on Linux at all. it's giving "it depends" and we respect that. 💅

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✨ NAME ✨

iswalnum, iswalnum_l — test for an alphanumeric wide-character code. that's it. that's the job. 🎀

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🫶 SYNOPSIS 🫶

#include <wctype.h>

int iswalnum(wint_t wc);
int iswalnum_l(wint_t wc, locale_t locale);

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🌸 DESCRIPTION 🌸

okay so first, for iswalnum() specifically: the functionality described on this reference page is aligned with the ISO C standard. if there's any conflict between what's written here and the ISO C standard, that conflict is unintentional — no drama intended, fr fr. this volume of POSIX.1‐2017 defers to the ISO C standard. periodt. 👑

now the actual tea ☕: the iswalnum() and iswalnum_l() functions shall test whether wc is a wide-character code representing a character of class alpha or digit in the current locale, or in the locale represented by locale, respectively. (yes, respectively — iswalnum() does current locale, iswalnum_l() does the locale you handed it. slay.) for the full lore, see the Base Definitions volume of POSIX.1‐2017, Chapter 7, Locale.

so the wc argument is a wint_t, and here's the thing — the application shall make sure that value is a wide-character code corresponding to a valid character in the locale used by the function, or it's equal to the value of the macro WEOF. if the argument has any other value, the behavior is undefined. 😭 so like, don't be chaotic about it.

also, HUGE warning bestie: the behavior is undefined if the locale argument to iswalnum_l() is the special locale object LC_GLOBAL_LOCALE or if it's not a valid locale object handle. like, undefined undefined. don't do it. 🙈

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💜 RETURN VALUE 💜

the iswalnum() and iswalnum_l() functions shall return non-zero if wc is an alphanumeric wide-character code; otherwise, they shall return 0. simple as that, no cap. ✨

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💀 ERRORS 💀

no errors are defined. nothing. zero. the void. 🕳️

the following sections are informative. (iykyk — that means they're the bonus content, not the rules.) 📝

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🦋 EXAMPLES 🦋

None. yeah, literally none. we're keeping it mysterious. 🎀

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🌈 APPLICATION USAGE 🌈

to make sure your applications stay portable — especially across natural languages, which is a whole vibe — only these functions and the functions in the reference pages listed in the SEE ALSO section should be used for character classification. so like, stay in your lane bestie, it's for your own good. 🫶

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🧚 RATIONALE 🧚

None. iconic silence. 💅

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⭐ FUTURE DIRECTIONS ⭐

None. the future is undefined and honestly? same. 🔥

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👑 SEE ALSO 👑

• iswalpha()
• iswcntrl()
• iswctype()
• iswdigit()
• iswgraph()
• iswlower()
• iswprint()
• iswpunct()
• iswspace()
• iswupper()
• iswxdigit()
• setlocale()
• uselocale()

and also, from the Base Definitions volume of POSIX.1‐2017:

• Chapter 7, Locale
• <locale.h>
• <stdio.h>
• <wctype.h>

go read all of them, bestie, they're all connected like a group chat. 🫂

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📜 COPYRIGHT 📜

okay legal bestie moment, we gotta do this part properly:

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 .

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and that's the whole page, bestie!! 🎀 this absolute icon of a manpage came to you from IEEE/The Open Group, dated 2017, and it's filed under ISWALNUM(3POSIX). go test some wide characters, you're gonna eat. 💅✨🦋