wcsspn(3)

✨ wcsspn(3) ✨

okay bestie, gather round, because today we're talking about wcsspn from the Library Functions Manual — she lives in the Standard C library (libc, link with -lc) and she is so much chiller than her name makes her look 💖

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🎀 NAME 🎀

wcsspn — get the length of a prefix wide-character substring. that's it. that's the job. very demure, very mindful 💅

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📚 LIBRARY 📚

Standard C library (libc, -lc) 🫶

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🌸 SYNOPSIS 🌸

#include <wchar.h>

size_t wcsspn(const wchar_t *wcs, const wchar_t *accept);

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💖 DESCRIPTION 💖

okay so. wcsspn() is literally the wide-character version of strspn(3) ✨ — like, same energy, but for wide chars.

Here's the vibe: it goes through wcs from the very start and asks "how far can I walk while every single character I step on is on the guest list?" The guest list is accept. The second it hits a wide character that is not listed in accept, it stops and tells you how many steps it took. 🚶♀️

So basically it determines the length of the longest initial segment of wcs that's made up entirely of wide characters listed in accept. In other words: it searches for the first occurrence, inside the wide-character string wcs, of a wide character that is not contained in the wide-character string accept. no cap 🔥

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🦋 RETURN VALUE 🦋

wcsspn() returns the number of wide characters in that longest initial segment of wcs which consists entirely of wide characters listed in accept. 💯

Or, said the other way (same tea, different mug): it returns the position of the first occurrence in the wide-character string wcs of a wide character that is not contained in the wide-character string accept — or, if there is no such character at all, it returns wcslen(wcs). 🌈

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👑 ATTRIBUTES 👑

for the explanation of the terms used in this section, go check out attributes(7) bestie 🫶

• Interface: wcsspn()
  • Attribute: Thread safety
  • Value: MT-Safe ✨

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💜 STANDARDS 💜

• C11
• POSIX.1-2008

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🌟 HISTORY 🌟

• POSIX.1-2001
• C99

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🔍 SEE ALSO 🔍

• strspn(3)
• wcscspn(3)

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aaand that's the whole page, bestie 💖 that was Linux man-pages 6.20, dated 2026-02-08 — and yes, the page is literally called wcsspn(3), the way that it ate and left no crumbs 👑✨💅