Data structure
- 2. Data Structure A Data Structure is a particular way of organizing data in a computer so that it can be used effectively. For Example : we can store a list of items having the same data-type using the array data structure. U B F D A E C . . .
- 3. Dynamic Allocation Memory Function Code Task Malloc() ptr = (cast-type*) malloc(byte-size) Allocates request size of bytes and returns a pointer to the first bytes of the allocated Space. Calloc() ptr = (cast-type*)calloc(n, element-size); Allocates space for an array of elements, initializes them to zero and then returns a pointer to the memory.
- 4. Function Code Task Free() free(ptr); Frees previously allocated space. Realloc() ptr = realloc(ptr, newSize); Modifies the size of previously allocated space.
- 5. • A linked list is a series of connected nodes • Each node contains at least – A piece of data (any type) – Pointer to the next node in the list • Head: pointer to the first node • The last node points to NULL
- 6. Single Linked List • Singly linked list is a collection of nodes linked together in a sequential way where each node of singly linked list contains a data field and an address field which contains the reference of the next node. Circular Linked List • The last node points to the first node of the list • How do we know when we have finished traversing the list? (Tip: check if the pointer of the current node is equal to the head.) Doubly linked lists • Each node points to not only successor but the predecessor • There are two NULL: at the first and last nodes in the list • Advantage: given a node, it is easy to visit its predecessor. Convenient to traverse lists backwards
- 7. Single Linked List • A linked list we must keep track/reference of the first node which may be referred by head pointer variable. In singly linked list address field of last node must contain a NULL value specifying end of the list. struct node { int data; //Data node * next; // Address };
- 8. Circular Linked List I. A circular linked list is basically a linear linked list that may be singly or doubly. The only difference is that there is no any NULL value terminating the list. In fact in the list every node points to the next node and last node points to the first node, thus forming a circle. Since it forms a circle with no end to stop hence it is called as circular linked list. • Algorithm to create circular linked list • %%Input : N {Total number of nodes to be created} • Being: alloc (head) • read (data) • head.data ← data; • head.next ← NULL; • prevNode ← head; • For count ← 2 to N do alloc (newNode) • read (data) newNode.data ← data; • newNode.next ← NULL; • prevNode.next ← newNode; • prevNode ← newNode; • End for • prevNode.next ← head; • End
- 9. Doubly linked list Doubly linked list is a collection of nodes linked together in a sequential way. Each node of the list contains two parts (as in singly linked list) data part and the reference or address part. The basic structure of node is shown in the below image: struct node { int data; // Data field struct node * prev; // Address of previous node struct node * next; // Address of next node };