SE250:lab-4:apra102

Task 1

Hmmmmm to start with when I looked at the lab tasks sheet I am kind of lost, later I read the whole paper twice that i could do that lab with in time. This is a lengthy. I find this lab really hard to understand. Especially tasks after 3. Any how i tried to manage up to task 4 but later I am lost. I really had a hard time to understand this linked lists especially that find and copy list. To find the length of list I wrote a function as follows:

int length(Cons* list) {
	int len =0;
	for( ; list!=nil; list =list->tail){
		len++;
	}
	return len;
}

Task 2

To find the elements in the named functions I tried for a long time. I got the concept theoretically but I was unable to code it. But when I asked the tutor it seemed to be really easy. And I came up with the code as follows:

element_t first(Cons* list){
	return list->head;
}

element_t second(Cons* list){
	return list->tail->head;
}

element_t third(Cons* list){
	return list->tail->tail->head;
}

element_t fourth(Cons* list){
	return list->tail->tail->tail->head;
}

Task 3

I even really had a hard time understanding this nth element. Which I really couldn't do for a long time, finally I came up with the following code:

element_t nth(int i, Cons* list){
	while(i !=0){
		list = list->tail;
		i--;
	}
 	return list->head;
}

Task 4

Equal function, by the time i came up to this task I am short of time to complete the rest of tasks, but still i tried to do that for a while, I got up to certain point. Should make a function that returns true or false. So, I should use a ‘for’ or a 'While' loop thats what I got in my mind. I got an idea but hard to put in to a code. I got the following as code for this:

int equal(Cons* list1, Cons* list2){
	while((list1 !=nil) && (list2 !=nil)){

		if(list1->head ==list2->head){
			list1 = list1->tail;
			list2 = list2->tail;
			return 1;
		}
 		else{
			return 0;
		}
	}
	
}

Up to here I did quite ok. But later i couldn't do any thing.

Main Function

int main( ) {
    Cons* list  =  cons(1,cons(2,cons(3,nil)));
    Cons* list2  =  cons(4,cons(5,cons(7,nil)));
    Cons* list3  =  cons(1, cons(2,cons(3,cons(4,nil))));
    Cons* search;

    print_list(list ); /* expect: List[1,2,3] */
    printf("Length = %d\n", length( list )); /* should return 3 */
    printf("%d\n",first(list));
    printf("%d\n",second(list));
    printf("%d\n", third(list));
    printf("%d\n", fourth(list));
    printf("%d\n", nth(1, list));
    printf("%d\n", nth(2, list));
    printf("%d\n", nth(0, list));

    printf("\nEqual test:\n");
    printf("%d\n", equal(list, list2));
    printf("%d\n", equal(list, list3));
    printf("%d\n", equal(list, list));
    printf("%d\n", equal(list2, list3));
    return 0;
}

I used these printf functions to test my functionswhich I did up to now.

Conclusion

Over all I found this lab lengthy. But a good exercise on linked lists. It was a good lab to understand how these Linked Lists works but, up to now I don't have a clear idea how to do these stuff work. But in the next lecture when the lecture taught about the whole copy, find and lookup functions i got an idea, but still I need some practice on this topic and a clear idea of what I am suppose to do.