MEMMEM(3) Library Functions Manual MEMMEM(3)

memmem — locate a byte substring in a byte string

#include <string.h>

void *
memmem(const void *big, size_t big_len, const void *little, size_t little_len);

The () function locates the first occurrence of the byte string little in the byte string big.

If little is zero length, big is returned; if little occurs nowhere in big, NULL is returned; otherwise a pointer to the first character of the first occurrence of little is returned.

memchr(3), strchr(3), strstr(3)

The memmem() function conforms to IEEE Std 1003.1-2024 (“POSIX.1”).

The memmem() function first appeared in OpenBSD 5.4.

OpenBSD 7.8 June 13, 2025 MEMMEM(3)