Lecture on Linked List Implementation

Introduction

• Previous lessons covered:
  • Description of linked lists
  • Cost of operations in linked lists
  • Comparison between linked lists and arrays
• Current focus: Implementing linked lists in C/C++
• Prerequisites:
  • Knowledge of pointers in C/C++
  • Understanding of dynamic memory allocation

Key Concepts in Linked Lists

• Data Storage: Data is stored in non-contiguous memory blocks called nodes.
• Node Structure:
  • Each node has two parts:
    • Data field
    • Address field (link to next node)
• Address Randomness:
  • Addresses of memory blocks are random; no order or adjacency.
• Head Node:
  • Identity of linked list is the address of the first node (head node).
  • A pointer to the head node serves as the linked list identity.

Implementation in C/C++

Structure Definition

• C Implementation:
  • Use struct to define a node with int data and struct node* link.
• C++ Implementation:
  • Use Node* for pointer to node, similar to struct node* in C.*

Creating and Managing Nodes

• Declaring a Head Node Pointer:
  • Initialize a pointer (e.g., A) to the head node and set it to NULL.
• Node Creation:
  • Use malloc in C to allocate memory, size equal to a node.
  • Use new in C++ for cleaner memory allocation.

Node Insertion

• Single Node Insertion:
  • Create a node, populate data, and adjust links.
  • Use temporary pointer (temp) to store address during setup.
  • Adjust the head node pointer (A) to point to new node.
• Alternate Syntax:
  • Using -> operator for field access in C++.

Inserting Multiple Nodes

• Logic for Multiple Insertions:
  • Insert at the end of the list using traversal logic.
  • Create node, traverse to end, update last node’s link.
• Sample Code Structure:
  • Use temporary pointer (temp1) for traversal.
  • Protect head node pointer (A) from being modified.

Traversal Logic

• While Loop for Traversal:
  • Use a loop to traverse to the end of the list.
  • Use a temporary pointer to avoid losing the head node’s address.
• Printing Elements:
  • Print data using temp->data within the loop.

Future Lessons and Enhancements

• Develop functions for:
  • Printing elements in the list
  • Inserting at the beginning or at a specific position
• Explore code implementation in coming lessons.