memchr(3)

✨ memchr(3) — the girlies' guide to finding a byte in memory ✨

okay so bestie, you know how sometimes you've got a big ol' blob of memory and you're like "where tf is that one specific character"?? that's literally what memchr is for 💅 she's a libc classic, she's from the Library Functions Manual, and she is so good at her job.

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🌸 NAME 🌸

memchr — memory search character 🎀

💖 LIBRARY 💖

Standard C library (libc, -lc) — the og, the icon, the one that's already on your machine bestie 🫶

🦋 SYNOPSIS 🦋

#include <string.h>  // see memory.h(3head)

void *memchr(size_t n;
             const void s[n], int c, size_t n);

yes the #include line really do be looking like that, and yes there is a little comment telling you to go read memory.h(3head), we love a cross-reference 💖

🔥 DESCRIPTION 🔥

so here's the tea ☕ memchr() scans the first n bytes of the memory area that s points to, looking for the first instance of c. first one only, she's not doing a whole collection tour, she finds the match and she leaves 👑

and the little detail that matters: both c and the bytes of the memory area pointed to by s get interpreted as unsigned char. no signed weirdness, no vibes-based guessing, just clean unsigned bytes ✨

⭐ RETURN VALUE ⭐

memchr() hands you back a pointer to the matching byte 🎉 or NULL if that character just straight up does not occur in the given memory area 😭 (it happens to the best of us)

👑 ATTRIBUTES 👑

for an explanation of the terms used in this section, go peek at attributes(7) bestie.

• memchr() — Thread safety: MT-Safe 💅 (she is safe to use across threads, periodt)

🌈 STANDARDS 🌈

C11, POSIX.1-2008. she is certified, she is official, she has receipts 🧾✨

🎀 HISTORY 🎀

POSIX.1-2001, C89, SVr4, 4.3BSD. yeah she's been around since literally forever, an elder icon, we stan a legacy queen 👑

🫶 SEE ALSO 🫶

• memory.h(3head)
• memrchr(3)
• wmemchr(3)

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ngl if you need to search backwards from the end, that's a memrchr(3) situation, and if you're doing wide characters that's wmemchr(3) territory. choose your fighter 💜

and that's the whole page bestie, no cap fr fr 🌸💖✨

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signing off from Linux man-pages 6.20, dated 2026-08-10 — mwah, stay safe out there and don't forget to check your return value 💅🎀🦋