Introduction to Data Structures

What are Data Structures?

A Data Structure is a particular way of storing and arranging data in a computer so it can be accessed and modified efficiently.

• Defines how data is stored
• Defines how data is accessed
• Defines how data is manipulated
• Improves performance of algorithms

Why Do We Need Data Structures?

• To store large amounts of data efficiently
• To perform operations quickly
• To reduce memory usage
• To increase program performance
• To handle complex problems easily

Types of Data Structures

Data structures are mainly divided into two categories:

• 1. Primitive Data Structures   → int, float, char, double
• 2. Non-Primitive Data Structures   Includes:
  • Arrays
  • Strings
  • Structures
  • Linked Lists
  • Stacks
  • Queues
  • Trees
  • Graphs

Linear vs Non-linear Data Structures

Linear Data Structures

Elements arranged in a sequence.

• Array
• String
• Linked List
• Stack
• Queue

Non-Linear Data Structures

Elements arranged hierarchically.

• Tree
• Graph

Applications of Data Structures

• Searching and Sorting
• Databases and File System organization
• Compiler design
• Operating system (process management)
• Networking (routing tables)
• Artificial Intelligence and Machine Learning
• Game development

Basic Example: Array as a Data Structure

#include <stdio.h>

int main() {

    int marks[5] = {90, 85, 92, 88, 95};
    
    for(int i = 0; i < 5; i++){
        printf("%d ", marks[i]);
    }

    return 0;
}

Basic Example: Linked List Node

#include <stdio.h>
#include <stdlib.h>

struct Node {
    int data;
    struct Node* next;
};

int main() {

    struct Node* head = (struct Node*) malloc(sizeof(struct Node));
    
    head->data = 10;
    head->next = NULL;
    
    printf("Node value: %d", head->data);

    free(head);
    return 0;
}

Practice Questions

1. What is a data structure? Explain with examples.
2. Difference between linear and non-linear data structures.
3. List five real-life applications of data structures.
4. Explain the importance of data structures in programming.
5. What is the difference between primitive and non-primitive data structures?

Practice Task