NAME

       memmem - locate a substring

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

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

       void *memmem(size_t hsize, size_t nsize;
                    const void haystack[hsize], size_t hsize,
                    const void needle[nsize], size_t nsize);

DESCRIPTION

       The  memmem()  function  finds the start of the first occurrence of the substring needle of size nsize in
       the memory area haystack of size hsize.

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 6.15                               2025-06-28                                          memmem(3)