Dynamic Memory

Dynamic Memory

used to allocate elements in data structures

use pointers between dynamic instances to organise our data structure

Building a Dynamic ‘Singly Linked’ List

we can start with ‘no items’ 

and build up our data structure one item at a time

Chaining Nodes / Growing the List

e.g. Allocate a new node (using malloc)

‘chain it’ so our first item points to the new item

General Rules

allocate space for a ‘node’ (a struct) of the appropriate type

find where to add our item (start, end, insertion point)

adjust the pointers to stay consistent with the type of data structure we’re working with

In Memory

• as the data structure grows, we allocate more ‘blocks’ of dynamic memory

• we chain these together to form our data structure

• we need to be careful to manage our pointers and hand memory back to the memory allocator

Declaring a ‘node’ struct in C

//define listItem node type
struct listItem {
char name [20];
char college [20];

//self-referential pointer
struct listItem *next; 
};

Declaring a variable (head pointer) in C

int main()
{
struct listItem *head = NULL;
}