Singly Linked Lists

Properties:
- Efficient addition and removal from any position
- Linear traversal to access arbitrary elements
- Efficient dynamic expansion
List representation:
struct host_list {
struct host_list *next;
struct in_addr addr;
} *hosts;
Traversal:
int
search_host(addr)
        struct in_addr addr;
{
        struct host_list *hp;

        if (!hosts)
                return(0);

        for (hp = hosts; hp != NULL; hp = hp->next) {
                if (hp->addr.s_addr == addr.s_addr)
                        return(1);
        }
        return(0);
}
Element addition:
void
remember_host(addr)
        struct in_addr addr;
{
        struct host_list *hp;

        if (!(hp = (struct host_list *)malloc(sizeof(struct host_list)))) {
                err(1, "malloc");
                /* NOTREACHED */
        }
        hp->addr.s_addr = addr.s_addr;
        hp->next = hosts;
        hosts = hp;
}