iswctype(3)

✨ iswctype — wide-character classification ✨

okay bestie, gather round, because today we're learning about iswctype(3), which lives in the Library Functions Manual and honestly? She's a vibe. 💅

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🌸 LIBRARY 🌸

Standard C library — that's libc, and you link it with -lc. iconic behavior, no notes. 🫶

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🎀 SYNOPSIS 🎀

#include <wctype.h>

int iswctype(wint_t wc, wctype_t desc);

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💖 DESCRIPTION 💖

so here's the tea. You hand iswctype() a wide character in wc, plus a character property descriptor in desc, and it's basically doing a vibe check: does this character belong to the class that desc is describing? 🌈

If yes — if wc is a wide character that has the character property designated by desc (or, put another way, belongs to the character class designated by desc) — then iswctype() returns nonzero. Slay.

Otherwise? It returns zero. Not slay.

And one more thing, bestie, don't sleep on this: if wc is WEOF, zero is returned. Every single time. No exceptions. 💀

also — and this is the part where you have to pay attention — desc must be a character property descriptor returned by the wctype(3) function. Like, it has to be one of those. Don't be out here making up your own descriptors, that's not the move. 🙈

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⭐ RETURN VALUE ⭐

• iswctype() returns nonzero if wc has the designated property. 🎉
• Otherwise, it returns 0.

that's it. that's the whole return value situation. periodt. 👑

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🔥 ATTRIBUTES 🔥

ngl, if any of these terms are confusing you, the glossary lives over in attributes(7), go check her out. 📚

• iswctype() — Thread safety: MT-Safe

translation: she's thread-safe. multiple threads can pull up at the same time and nobody's gonna have a bad time. 💯

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🦋 STANDARDS 🦋

• C11
• POSIX.1-2008

certified, standardized, main character energy. 👑

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🌈 HISTORY 🌈

She's been around a minute, fr fr:

• POSIX.1-2001
• C99

elder icon behavior honestly. 🎀

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💜 NOTES 💜

okay so this is the part people forget and then they're confused later: the behavior of iswctype() depends on the LC_CTYPE category of the current locale. 🌍

so like, the same character can get a totally different answer depending on where in the world your locale thinks it is. it's giving "context matters." don't forget it. 💅

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🧚 SEE ALSO 🧚

the whole girl gang, all of them:

• iswalnum(3)
• iswalpha(3)
• iswblank(3)
• iswcntrl(3)
• iswdigit(3)
• iswgraph(3)
• iswlower(3)
• iswprint(3)
• iswpunct(3)
• iswspace(3)
• iswupper(3)
• iswxdigit(3)
• wctype(3)

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lowkey reminder bestie: desc comes from wctype(3). pair them up like the iconic duo they are. 🫶

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okay that's the whole page, mwah. 💋 this one came to you courtesy of Linux man-pages 6.20, dated 2026-02-08 — and yes, that's iswctype(3), we been knew. 🎀✨🦋