void *my_memcpy(void *dst, void* src, int size){ int len = sizeof(long); long *pdst = (long*)dst; long *psrc = (long*)src; for (; size >= len; ++pdst, ++psrc, size -= len) { *pdst = *psrc; } for (len = size, size = 0; size < len; ++size) { *((char*)pdst + size) = *((char*)psrc + size); } return dst;}int main(){ char src[] = "hello", dst[10] = {" "}; my_memcpy(dst, src, 5); printf("dst = %s ", dst); return 0;}