Notes on Arrays in Data Structure

Introduction

• Welcome to Simply Learn's YouTube channel.
• Today's topic: Arrays in Data Structures.
• Agenda:
  1. Purpose of Arrays
  2. What is an Array?
  3. Types of Arrays
  4. Declaration of Arrays
  5. Initialization of Arrays
  6. Accessing Array Elements
  7. Basic Operations on Arrays
  8. Advantages and Disadvantages of Arrays
  9. Key Takeaways

1. Purpose of Arrays

• Need for arrays arises when handling multiple data points.
• Example: Storing scores of multiple students without creating numerous variables.
• Arrays allow collective storage and operations on large data sets efficiently.

2. What is an Array?

• An array is a linear data structure that stores elements sequentially.
• Elements are stored in adjacent memory locations.
• Arrays store only one data type (e.g., character, integer).

Memory Representation

• Declared array (e.g., character array): ['a', 'r', 'r', 'a', 'y']
• Array elements are accessible via indexes; index starts from 0.
• Lower Bound: First index (0)
• Upper Bound: Last index (n-1)

3. Types of Arrays

3.1 One-Dimensional Arrays

• Require one subscript for declaration.
• Example: int marks[5];

3.2 Multi-Dimensional Arrays

• Consist of multiple rows and columns.
• 2D Arrays: Represented as a matrix (rows and columns).
  • Example: int matrix[3][3];
• 3D Arrays: Collection of 2D arrays requiring three subscripts.

4. Declaration of Arrays

• Syntax to declare an array:
  data_type array_name[size];
• Example: int example[6];
  • It allocates memory for 6 integer values.

5. Initialization of Arrays

• Multiple methods to initialize arrays:
  1. Direct assignment: int a[5] = {1, 2, 3, 4, 5};
  2. Without size: int a[] = {1, 2, 3, 4, 5};
  3. Allocating elements individually.
  4. Using a loop for initialization.

6. Accessing Array Elements

• Accessing elements requires the array name and index:
  • Example: xyz[0] accesses the first element.

7. Basic Operations on Arrays

7.1 Traversal

• Visiting each element of the array sequentially.

7.2 Insertion

• Adding elements at beginning, end, or a specific location.
• Example programs were demonstrated for each scenario.

7.3 Deletion

• Removing elements from beginning, end, or a specific index.

7.4 Searching

• Finding a specific value in the array and checking for existence.

7.5 Sorting

• Organizing array elements in a specified order (ascending/descending).

8. Advantages of Arrays

• Store multiple elements of the same data type.
• Random access via index.
• Predefined memory allocation (no memory overflow).
• Efficient representation of tabular data (e.g., 2D arrays).

9. Disadvantages of Arrays

• Size must be predefined; cannot be altered.
• Static nature can lead to memory waste if not all allocated space is used.
• Insertion and deletion operations can be complex due to sequential storage.

10. Key Takeaways

• Understand the necessity and structure of arrays.
• Learn how to declare, initialize, and perform operations on arrays.
• Recognize the advantages and disadvantages of using arrays.

---

• For questions or further clarifications, please comment below.
• Thank you for attending the lecture!