ISALPHA(3P)

💖 ISALPHA(3P) — bestie edition 💖

okay so this is from the POSIX Programmer's Manual, and we're talking about isalpha, isalpha_l — the little functions that answer the question "is this an alphabetic character?" 👑

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🚨 PROLOG 🚨

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (so like, go check the corresponding Linux manual page for the deets on Linux behavior, bestie), or honestly the interface may not even be implemented on Linux at all. 🙈

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✨ NAME ✨

isalpha, isalpha_l — test for an alphabetic character 🌸

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🎀 SYNOPSIS 🎀

#include <ctype.h>

int isalpha(int c);
int isalpha_l(int c, locale_t locale);

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💅 DESCRIPTION 💅

So for isalpha(): the functionality described on this reference page is aligned with the ISO C standard. And like, any conflict between the requirements described here and the ISO C standard? Totally unintentional, not a vibe we're going for. This volume of POSIX.1‐2017 defers to the ISO C standard. periodt.

The isalpha() and isalpha_l() functions shall test whether c is a character of class alpha in the current locale, or in the locale represented by locale, respectively. (go look at the Base Definitions volume of POSIX.1‐2017, Chapter 7, Locale for the lore 📖)

The c argument is an int, and the value of which the application shall ensure is representable as an unsigned char or equal to the value of the macro EOF. If the argument has any other value... 🫣 the behavior is undefined. not a drill.

⚠️ And also — the behavior is undefined if the locale argument to isalpha_l() is the special locale object LC_GLOBAL_LOCALE, or is not a valid locale object handle. so don't do that. fr fr.

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🔥 RETURN VALUE 🔥

The isalpha() and isalpha_l() functions shall return non-zero if c is an alphabetic character; otherwise, they shall return 0. it's giving yes/no, iconic behavior tbh 💖

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💀 ERRORS 💀

No errors are defined. (ngl, a rare chill moment)

The following sections are informative. 👇

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🍓 EXAMPLES 🍓

None. 😭 nothing to see here bestie, move along

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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. iykyk. don't get cute with it. 🧚

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⭐ RATIONALE ⭐

None.

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🦋 FUTURE DIRECTIONS 🦋

None.

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👑 SEE ALSO 👑

isalnum(), isblank(), iscntrl(), isdigit(), isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(), isxdigit(), setlocale(), uselocale()

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

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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 🫶 go forth and classify characters responsibly — this was IEEE/The Open Group, 2017, the ISALPHA(3P) page itself, signing off ✨💖🎀