wctob(3)

✨ wctob — the "can I squish this wide char into ONE lil byte" test ✨

okay bestie, gather round, because we're talking about wctob, a function from the Standard C library (libc, -lc) that you are literally never supposed to use 💖 like the manpage itself says "Never use this function" and we will get to that, don't worry.

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🌸 SYNOPSIS 🌸

#include <wchar.h>

int wctob(wint_t c);

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🦋 DESCRIPTION 🦋

so like. wctob() checks whether the multibyte representation of the wide character c — starting from the initial state — is just a single byte. that's it, that's the whole job 🎀

if it is? slay. it gets returned as an unsigned char. one byte. tiny. adorable. 💅

but here's the part where the manpage puts its hand on your shoulder and looks you dead in the eye:

Never use this function. 🚨 It cannot help you in writing internationalized programs. Internationalized programs must never distinguish single-byte and multibyte characters.

so like. it's giving "built different but in a bad way." it exists, it's real, it's not your friend 🙈

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💖 RETURN VALUE 💖

wctob() gives you back the single-byte representation of c if it exists, and EOF otherwise. no in-between, no maybe, no "it depends" (okay well actually it does depend on the locale, more on that in a sec 👀).

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👑 ATTRIBUTES 👑

for what all these fancy words even mean, go peek at attributes(7) 🤓

• wctob() — Thread safety: MT-Safe ✅ she's thread safe, that's genuinely her one good quality bestie.

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🌈 STANDARDS 🌈

• C11
• POSIX.1-2008

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🎀 HISTORY 🎀

• POSIX.1-2001
• C99

she's been around. legacy icon behavior. unslay of her honestly. ⭐

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🧚 NOTES 🧚

• the behavior of wctob() depends on the LC_CTYPE category of the current locale. so like, the vibe is locale-dependent, which is exactly the kind of chaos you don't want fr fr 😭
• and again, because it bears repeating: this function should never be used. internationalized programs must never distinguish single-byte and multibyte characters. instead use either wctomb(3) or the thread-safe wcrtomb(3) — those are the actual main characters here. periodt. 👑

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💜 SEE ALSO 💜

• btowc(3)
• wcrtomb(3)
• wctomb(3)

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and that's the teaaa 🫶 this lil page came from Linux man-pages 6.20, dated 2026-02-08, and it's all about wctob(3). love u, go use wcrtomb(3) instead, mwah 💋🌸✨