this is my name
this is my email
this is my face
this is my intro

Stealing this thanks Gal ~

This tut/lab focused on revising linked lists, circular linked lists and double linked lists.

Duplicating / cloning a linked list

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47

// Creates a new node, initialised with the item provided.
// Returns pointer to node (link).
link node_new (Item item)
{
    link n = malloc (sizeof (*n));
    if (n == NULL)
        err (1, "couldn't allocate");
    n->item = item;
    n->next = NULL;
    return n;
}

// Insert a new node into a given non-empty list.
// The node is inserted directly after the head of the list ls.
void list_insert_next (link ls, link node)
{
    assert (ls != NULL);
    assert (node != NULL);
    node->next = ls->next;
    ls->next = node;
}


/* ... */

link duplicateList(link ls) {
  // if given an empty list, return NULL
  if (!ls) return NULL;

  // Create a new node with the item of the frst item
  link head = node_new(ls->item);
  
  // Set pointer to the last element of the new list
  link ptr = head;

  // Set a pointer to the next element of the original list
  link cursor = head->next;

  // Move through the list and clone the items
  while (cursor) {
    list_insert_next(node_new(cursor->item), ptr)  
    ptr = ptr -> next;
    cursor = cursor -> next;
  }

  return head;
}

Reversing a linked list

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13

int main (int argc, char *argv[])
{
    link ls = list_from_cstr ("hello world!");
    link ls2 = list_duplicate (ls);

    list_print (ls);
    list_print (ls2);
    list_print (list_reverse (ls));
    list_print (ls);
    list_print (ls2);

    return 0;
}

hello world!
hello world!
!dlrow elloh
h <– ls1 still points to the h node hello world!

Double linked list

e.g linked lists with next and prev

1
2
3
4
5
6
7

typedef char Item;
typedef struct dnode *dlink;

struct dnode {
    Item item;
    dlink prev, next;
};

Write a function append which attaches the list list2 at the end of list1 and returns the resulting list.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12

dlink append (dlink list1, dlink list2) {
  if (!list1) return list2;
  if (!list2) return list1;

  dlink last = list1;
  for(; last->next; last=last->next); // while (last->next) last = last->next;
  
  last->next = list2;
  list2->prev = last;

  return list1;
}

Is it necessary to return the resulting list?
Could we instead get away with the following interface?
void append (dlink list1, dlink list2);

– We could.

Switch statements

switch (variable) {…}
–> if A else if B else if C else if D else …

The break statement; execution fall-through

break exits a switch statement.

If it is not present, the execution can continue into other statements.
This could be beneficial in some cases

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13

speed = 200;
switch (speed) {
  case 200:
    printf("You're going REALLY REALLY fast\n")
  case 150:
    printf("You're going REALLY fast\n")
  case 100:
    printf("On your green Ps?\n")
  case 90:
    printf("Hah learner's license\n")
  case 40:
    printf("ScHoOl ZoNe SpEeD\n")
}

You're going REALLY REALLY fast
You're going REALLY fast
On your green Ps?
Hah learner's license
ScHoOl ZoNe SpEeD

return (functions only)

We can use a return statement in place of a break if our switch statement is the only code in a function

switch vs if/else

Using switch

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13

assert (islower (ch));
switch (ch) {
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
    printf ("vowel");
    break;
default:
    printf ("consonant");
    break;
}

Using if else

1
2
3

assert (islower (ch));
if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') printf("vowel");
else printf ("consonant");

Ternary operator

condition ? valueIfTrue : valueIfFalse

1
2
3
4
5

if (condition) {
  return valueIfTrue;
} else {
  return valieIfFalse;
}