memmem可以在mac上使用吗？

#include <stdio.h>
#include <string.h>

int main() {
    char str[] = "Hello, World!";
    char substr[] = "World";

    char *result = strstr(str, substr);

    if (result != NULL) {
        printf("Substring found at index: %ld\n", result - str);
    } else {
        printf("Substring not found\n");
    }

    return 0;
}

#include <stdio.h>
#include <string.h>

void* memmem_custom(const void* haystack, size_t haystack_len, const void* needle, size_t needle_len) {
    const char* h = haystack;
    const char* n = needle;

    if (needle_len == 0) {
        return (void*)haystack;
    }

    for (size_t i = 0; i <= haystack_len - needle_len; i++) {
        if (memcmp(h + i, n, needle_len) == 0) {
            return (void*)(h + i);
        }
    }

    return NULL;
}

int main() {
    char data[] = {0x11, 0x22, 0x33, 0x44, 0x55};
    char pattern[] = {0x33, 0x44};

    void* result = memmem_custom(data, sizeof(data), pattern, sizeof(pattern));

    if (result != NULL) {
        printf("Pattern found at index: %ld\n", (char*)result - data);
    } else {
        printf("Pattern not found\n");
    }

    return 0;
}