ISWDIGIT(3P)

💖 ISWDIGIT — the "is this a digit tho" check (POSIX Programmer's Manual, bestie edition) 💖

okay so before we even start, the vibe check: this page lives inside the POSIX Programmer's Manual, and the Linux version of this interface might do its own thing (so like, go read the matching Linux manual page for the deets on Linux behavior), OR it might not even be implemented on Linux at all. 🙈 just so we're clear, bestie.

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✨ PROLOG ✨

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

translation: don't @ me if Linux does it different, go check the Linux page, and also it might just... not exist there?? iconic behavior honestly.

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🌸 NAME 🌸

iswdigit, iswdigit_l — test for a decimal digit wide-character code

that's the whole job. is this wide char a digit. yes or no. that's it. that's the function.

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🎀 SYNOPSIS 🎀

#include <wctype.h>

int iswdigit(wint_t wc);
int iswdigit_l(wint_t wc, locale_t locale);

two functions, one job. one of them lets you pick the locale yourself, which is the ✨fancy✨ one.

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🦋 DESCRIPTION 🦋

So for iswdigit(): the functionality on this reference page is aligned with the ISO C standard. And if there's any conflict between what's written here and the ISO C standard? That conflict is unintentional, no cap. This volume of POSIX.1‐2017 defers to the ISO C standard. ISO C said it first, we're just vibing.

The iswdigit() and iswdigit_l() functions shall test whether wc is a wide-character code representing a character of class digit in the current locale, or in the locale represented by locale, respectively; see the Base Definitions volume of POSIX.1‐2017, Chapter 7, Locale. one checks your current locale, the other one checks the locale YOU handed it. main character energy.

The wc argument is a wint_t, the value of which the application shall ensure is a wide-character code corresponding to a valid character in the locale used by the function, or equal to the value of the macro WEOF. If the argument has any other value, the behavior is undefined. 💀 so like. valid wide char, or WEOF. those are your options. anything else is you playing yourself.

big scary warning: the behavior is undefined if the locale argument to iswdigit_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle. fr fr, don't do that. 🚫

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⭐ RETURN VALUE ⭐

The iswdigit() and iswdigit_l() functions shall return non-zero if wc is a decimal digit wide-character code; otherwise, they shall return 0.

non-zero = yes digit. 0 = no digit. simple as. 💅

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🍓 ERRORS 🍓

No errors are defined.

The following sections are informative.

not a single error to define. it's giving unbothered. ✨

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🌈 EXAMPLES 🌈

None.

literally none. we're keeping it mysterious. 🙈

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🫶 APPLICATION USAGE 🫶

To ensure applications portability, especially across natural languages, only these functions and the functions in the reference pages listed in the SEE ALSO section should be used for character classification.

so if you want your app to actually travel well across languages, stick to these functions + the SEE ALSO girlies. that's the squad. don't go rogue.

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🧚 RATIONALE 🧚

None.

no rationale. it simply is. periodt.

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👑 FUTURE DIRECTIONS 👑

None.

the future is empty, bestie. nothing coming. 🦋

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💜 SEE ALSO 💜

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

The Base Definitions volume of POSIX.1‐2017, Chapter 7, Locale, <locale.h>, <wctype.h>

go read those too, they're all part of the character-classification friend group. iykyk 💅

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📜 COPYRIGHT 📜

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!! brought to you by IEEE/The Open Group, 2017 — slay, we love a 2017 moment. 💖✨🎀🦋🌸 go classify some characters, you got this. 🫶