iswblank(3)

✨ iswblank(3) ✨ — the iswblank bestie from section 3 of the manual 💅

okay bestie, sit down, because today we're talking about iswblank, a little libc baddie that answers one very important question: is this wide character a blank, or is it not? 🎀

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🌸 NAME 🌸

iswblank — test for whitespace wide character

📚 LIBRARY 📚

Standard C library (libc, -lc)

🦋 SYNOPSIS 🦋

#include <wctype.h>

int iswblank(wint_t wc);

🧚 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

iswblank():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

like, if you don't define those, glibc is gonna be like "who r u" 🙈

💖 DESCRIPTION 💖

so. iswblank() is literally the wide-character equivalent of the isblank(3) function — same energy, wider characters. It tests whether wc is a wide character belonging to the wide-character class "blank". 🫶

The wide-character class "blank" is a subclass of the wide-character class "space". yes, it's giving nepo baby, but like, in a math way.

Because it's a subclass of the wide-character class "space", the wide-character class "blank" is disjoint from the wide-character class "graph" and therefore also disjoint from its subclasses "alnum", "alpha", "upper", "lower", "digit", "xdigit", "punct". no overlap, no crossover, they don't hang out. 💀

The wide-character class "blank" always contains at least the space character and the control character '\t'. periodt. 👑

🌈 RETURN VALUE 🌈

iswblank() returns nonzero if wc is a wide character belonging to the wide-character class "blank". Otherwise, it returns zero. It's a yes or a no bestie, no in-between. ✨

👑 ATTRIBUTES 👑

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

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

so like, it's thread-safe, but it's locale-thread-safe, if that makes sense. iykyk 💅

⭐ STANDARDS ⭐

POSIX.1-2008.

🕰️ HISTORY 🕰️

POSIX.1-2001. yeah, this one's been around a minute. iconic behavior honestly. 🎀

📝 NOTES 📝

The behavior of iswblank() depends on the LC_CTYPE category of the current locale. so like, change your locale, change your answers. it's giving ✨situationship with your environment variables✨.

🔥 SEE ALSO 🔥

isblank(3), iswctype(3)

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and that's the whole page, bestie!! this was the Linux man-pages 6.20 version, dated 2026-02-08. go forth and test your wide characters with confidence, mwah 💖💅🦋🌈✨