memmem(3) Library Functions Manual memmem(3) NAME memmem - locate a substring LIBRARY Standard C library (libc, -lc) SYNOPSIS #define _GNU_SOURCE /* See feature_test_macros(7) */ #include void *memmem(const void haystack[.haystacklen], size_t haystacklen, const void needle[.needlelen], size_t needlelen); DESCRIPTION The memmem() function finds the start of the first occurrence of the substring needle of length needlelen in the memory area haystack of length haystacklen. RETURN VALUE The memmem() function returns a pointer to the beginning of the substring, or NULL if the substring is not found. ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). +--------------------------------------------+---------------+---------+ |Interface | Attribute | Value | +--------------------------------------------+---------------+---------+ |memmem () | Thread safety | MT-Safe | +--------------------------------------------+---------------+---------+ STANDARDS None. HISTORY musl libc 0.9.7; FreeBSD 6.0, OpenBSD 5.4, NetBSD, Illumos. BUGS In glibc 2.0, if needle is empty, memmem() returns a pointer to the last byte of haystack. This is fixed in glibc 2.1. SEE ALSO bstring(3), strstr(3) Linux man-pages 6.7 2023-10-31 memmem(3)