rawmemchr(3)

💖 rawmemchr(3) — the Library Functions Manual page, but make it make sense 💖

okay bestie, sit down, hydrate, and let's talk about rawmemchr — a lil function from the Library Functions Manual section of your fave man pages. she's from the Standard C library (libc, -lc) and she is, and I say this with love, a menace. 🫶

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✨ NAME ✨

rawmemchr — memory raw search character 🔍

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📚 LIBRARY 📚

Standard C library (libc, -lc) 💅

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🌸 SYNOPSIS 🌸

#define _GNU_SOURCE  /* See feature_test_macros(7) */
#include <string.h>

[[deprecated]] void *rawmemchr(const void *s, int c);

okay so first thing: yes, that [[deprecated]] is right there in the synopsis. she is marked deprecated, and we'll get into why in a sec. and yeah, you need that #define _GNU_SOURCE line up top (peep feature_test_macros(7) for the whole lore), plus #include <string.h>. 🎀

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💅 DESCRIPTION 💅

rawmemchr() is giving memchr()'s chaotic cousin. It's similar to memchr(), BUT — and this is the whole personality — it assumes an instance of c lies somewhere in the memory area starting at the location pointed to by s. And when I say "assumes", I mean the programmer knows for certain. Like, knew knew. Not guessing. Not vibes-checking. Certain certain. 👑

And here's the part where you hold my hand: if an instance of c is not found, the behavior is undefined. Not an error code, not a NULL, not a sad little return value. Undefined. She will just keep vibing through your memory like she pays rent there. 💀

bestie please, use strlen(3) or memchr(3) instead. genuinely. i'm not being dramatic, i'm being a good friend. 😭

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🦋 RETURN VALUE 🦋

The rawmemchr() function returns a pointer to the matching byte. that's it, that's the whole return value, she's a simple girl ✨

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👑 ATTRIBUTES 👑

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

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

so yeah — MT-Safe, multi-thread safe, she can hang in the group chat with everybody at once, no drama. 🫶

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🌈 STANDARDS 🌈

GNU. 🇬🇳 (affectionate, that's just her house)

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⭐ HISTORY ⭐

glibc 2.1. — she's been here since glibc 2.1, an elder icon, a legacy queen 👑

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🎀 SEE ALSO 🎀

• memchr(3) — the responsible one
• strlen(3) — also the responsible one
• strnul(3) — her other cousin, also a little unhinged iykyk

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Linux man-pages 6.20 🌸 dated 2026-02-25 — that's the version and the date this page was serving, and that's a wrap bestie 💖✨ stay safe, don't call rawmemchr() unless you're absolutely certain, and go drink some water 🍓💜