1. Linked List Intro
CSCE 121
J. Michael Moore

2. Array Recall Linked List
Arrays are created to be a specific size. Once you run out of slots, you can’t add any more elements.
Now that you know how to use dynamic memory, you could create a new larger array and copy the elements over.
That’s what vector does!
Linked List
Can grow as large as needed.

3. Array Insert Insert 11 into the first position (i.e. index 0)1 2 3 4 5 6 9 7
Insert 11 into the first position (i.e. index 0)
Shift all elements
Insert

4. Array Insert Insert 11 into the first position (i.e. index 0)1 2 3 4 5 6 9 7
Insert 11 into the first position (i.e. index 0)
Shift all elements
Insert

5. Array Insert Insert 11 into the first position (i.e. index 0)1 2 3 4 5 6 9 7
Insert 11 into the first position (i.e. index 0)
Shift all elements
Insert

6. Array Insert Insert 11 into the first position (i.e. index 0)1 2 3 4 5 6 9 7
Insert 11 into the first position (i.e. index 0)
Shift all elements
Insert

7. Array Insert Insert 11 into the first position (i.e. index 0)1 2 3 4 5 6 9 7
Insert 11 into the first position (i.e. index 0)
Shift all elements
Insert

8. Array Insert Insert 11 into the first position (i.e. index 0)1 2 3 4 5 6 9 7
Insert 11 into the first position (i.e. index 0)
Shift all elements
Insert

9. Array Insert Insert 11 into the first position (i.e. index 0)1 2 3 4 5 6 9 7
Insert 11 into the first position (i.e. index 0)
Shift all elements
Insert

10. Array Insert Insert 11 into the first position (i.e. index 0)1 2 3 4 5 6 11 9 7
Insert 11 into the first position (i.e. index 0)
Shift all elements
Insert

11. Note: Data could be complex like a Class, or simple like an int.
Dynamic Alternative
Note: Data could be complex like a Class, or simple like an int.
Create Node
Contains Data
Contains Pointer/Reference to next element 11

12. Linked List
Program starts with a pointer to the first node in the list.
Normally pointer to start node is called head.
Set to nullptr if the list is empty.

13. Add Item to Front of List
Create a new node
Head ? ?

14. Add Item to Front of List
Create a new node
Set its value
Head ? 11

15. Add Item to Front of List
Create a new node
Set its value
Attach to list
Set Node’s next to head
Head ? 11

16. Add Item to Front of List
Create a new node
Set its value
Attach to list
Set Nodes next to head
Set Head to point to new node.
Head
What is this? ? 11

17. Add Item to Front of List
Create a new node
Set its value
Attach to list
Set Nodes next to head
Set Head to point to new node.
Head
What is this? 11
If it was added to an empty list…

18. Add Item to Front of List
Create a new node
Set its value
Attach to list
Set Nodes next to head
Set Head to point to new node.
Head
What is this? 11 33
If it was added to a non empty list…

19. Linked List vs. Array
I’m sure I forgot something, but you get the idea!
Linked List
Array
More memory
Faster to insert item in middle.
Slower to get to item in list.
Can grow as needed.
Less memory
Slower to insert item in middle.
Faster to get to item in list.
Fixed size.
When it runs out of room the vector class:
creates a new larger array on the heap
copies the values to the new one
deletes the old one
Vector uses an array,
but is resizable.
HOW?