ISWALPHA(3P)

🦋 ISWALPHA — the POSIX Programmer's Manual, bestie edition 🦋

okay so before we even get into it, quick heads-up about the manual name: this whole thing lives in the POSIX Programmer's Manual, and the page itself is ISWALPHA(3P). got it? good. let's go 💅

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✨ PROLOG ✨

ngl this part is important so don't skip it:

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.

lowkey a whole "it depends" moment but fr fr, go check your Linux page if you're on Linux. don't come for me. 🙈

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🌸 NAME 🌸

iswalpha, iswalpha_l — test for an alphabetic wide-character code

that's the whole vibe. we're checking if a wide char is alphabetic. iconic. ✨

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🎀 SYNOPSIS 🎀

#include <wctype.h>

int iswalpha(wint_t wc);
int iswalpha_l(wint_t wc, locale_t locale);

copy that exactly bestie, character for character, no editing, i'm watching 👀

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💖 DESCRIPTION 💖

okay so for iswalpha(): the functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2017 defers to the ISO C standard.

so basically ISO C is the referee, we're just the commentator 💀

The iswalpha() and iswalpha_l() functions shall test whether wc is a wide-character code representing a character of class alpha in the current locale, or in the locale represented by locale, respectively; see the Base Definitions volume of POSIX.1‐2017, Chapter 7, Locale.

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.

🚨 okay listen. if the argument has any other value, the behavior is undefined. not "a little weird". not "kinda buggy". undefined. don't do it. periodt.

The behavior is undefined if the locale argument to iswalpha_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.

that's two whole ways to get yourself into undefined-behavior territory, bestie. choose wisely 🫶

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⭐ RETURN VALUE ⭐

The iswalpha() and iswalpha_l() functions shall return non-zero if wc is an alphabetic wide-character code; otherwise, they shall return 0.

so: yes → non-zero. no → zero. that's the whole thing. slay. 💅

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🌈 ERRORS 🌈

No errors are defined.

The following sections are informative.

literally nothing to report. main character energy, zero drama ✨

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🍓 EXAMPLES 🍓

None.

yeah there's no examples. i know. i'm as devastated as you are 😭

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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.

read that again. only those. iykyk. don't go rogue with your own classification scheme and then act surprised when it breaks across languages. 🫠

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👑 RATIONALE 👑

None.

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💜 FUTURE DIRECTIONS 💜

None.

no future plans, she's perfect as she is. 💅

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🔥 SEE ALSO 🔥

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

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

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📜 COPYRIGHT 📜

okay bestie, legal time, don't scroll past this one:

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! 🎀 this absolute banger was brought to you by IEEE/The Open Group, dated 2017, filed under ISWALPHA(3P). stay alphabetic, stay valid, and for the love of everything keep your wint_t values legal 💖✨🦋