iswdigit(3)

✨ iswdigit(3) ✨

okay bestie, welcome to the iswdigit page 💖 this one lives in the Library Functions Manual, and it's genuinely one of the cutest little checks in <wctype.h>.

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🎀 NAME

iswdigit — test for decimal digit wide character

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📚 LIBRARY

Standard C library (libc, -lc)

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🫶 SYNOPSIS

#include <wctype.h>

int iswdigit(wint_t wc);

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💅 DESCRIPTION

So. iswdigit() is literally just the wide-character version of isdigit(3) — like, same energy, bigger characters. It tests whether wc is a wide character that belongs to the wide-character class "digit". That's it. That's the whole job. 👑

Now let's talk hierarchy, because the wide-character classes are giving family tree:

• The wide-character class "digit" is a subclass of the wide-character class "xdigit", and therefore also a subclass of "alnum", of "graph", and of "print".
• Because it's a subclass of "print", the wide-character class "digit" is disjoint from the wide-character class "cntrl".
• Because it's a subclass of "graph", "digit" is disjoint from "space" and its subclass "blank".
• Because it's a subclass of "alnum", "digit" is disjoint from "punct".
• And "digit" is disjoint from "alpha", which means it's also disjoint from "alpha"'s subclasses "lower" and "upper".

And the part you actually need to remember 🔥: the wide-character class "digit" always contains exactly the digits '0' to '9'. No surprises, no extra friends, no impostors. periodt.

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⭐ RETURN VALUE

iswdigit() returns nonzero if wc is a wide character belonging to the wide-character class "digit". Otherwise it returns zero. Binary queen behaviour honestly 💅

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🔍 ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

• Interface: iswdigit()
• Attribute: Thread safety
• Value: MT-Safe locale

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👑 STANDARDS

C11, POSIX.1-2008.

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🌸 HISTORY

POSIX.1-2001, C99.

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📝 NOTES

The behavior of iswdigit() depends on the LC_CTYPE category of the current locale. so like, set your locale bestie, that's the vibe check here 🦋

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🍓 SEE ALSO

• isdigit(3)
• iswctype(3)

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ngl this one is a short read and we ate. no cap 💜

and that's a wrap!! this was Linux man-pages 6.20, dated 2026-02-08 — mwah, go check a digit and stay iconic 🎀✨💖