Lesson 03: Array List & Its Operations (With Real-World Examples in C++)

Content List

1. Introduction to Array List

2. What is an Array List?

3. Importance of Array List

4. Characteristics of Array List

5. Array List vs Array

6. Operations on Array List

   • Insertion

   • Deletion

   • Traversal

   • Searching

   • Updating

7. Real-World Use Cases of Array List

8. Implementation of Array List in C++

9. Advantages and Limitations

10. Conclusion

1. Introduction to Array List

In modern software applications, data is rarely static. Programs often need to add, remove, or update elements dynamically. Traditional arrays have a fixed size, which makes them less flexible.
To overcome this limitation, the concept of an Array List is widely used.

2. What is an Array List?

Definition

An Array List is a dynamic data structure that stores elements in a contiguous memory location like an array but can grow or shrink in size automatically during runtime.

Unlike a simple array, an array list does not require the size to be defined in advance.

3. Importance of Array List

Why Array List is Important

• Dynamic resizing

• Efficient random access

• Easy insertion and deletion

• Widely used in real-world applications

Real-Life Example

• A shopping cart where items can be added or removed

• A playlist where songs change dynamically

• A student list that grows each semester

4. Characteristics of Array List

• Stores elements in contiguous memory

• Supports index-based access

• Automatically resizes when capacity is exceeded

• Maintains insertion order

• Allows duplicate elements

5. ArrayList vs. Array

6. Operations on ArrayList

6.1 Insertion Operation

Definition

Insertion adds a new element to the array list. If the list is full, it automatically increases its size.

Use Case

Adding a new product to an online store catalog.

C++ Example (Insertion)

#include <iostream>
using namespace std;

int main() {
    int arr[10] = {10, 20, 30};
    int size = 3;

    arr[size] = 40;
    size++;

    for(int i = 0; i < size; i++)
        cout << arr[i] << " ";

    return 0;
}

6.2 Deletion Operation

Definition

Deletion removes an element from a specified index and shifts remaining elements.

Use Case

Removing an item from a shopping cart.

C++ Example (Deletion)

#include <iostream>
using namespace std;

int main() {
    int arr[10] = {10, 20, 30, 40};
    int size = 4;
    int pos = 1;

    for(int i = pos; i < size - 1; i++)
        arr[i] = arr[i + 1];

    size--;

    for(int i = 0; i < size; i++)
        cout << arr[i] << " ";

    return 0;
}

6.3 Traversal Operation

Definition

Traversal means accessing each element of the array list one by one.

Use Case

Displaying all students in a class list.

C++ Example (Traversal)

#include <iostream>
using namespace std;

int main() {
    int arr[] = {5, 15, 25, 35};

    for(int i = 0; i < 4; i++)
        cout << arr[i] << " ";

    return 0;
}

6.4 Searching Operation

Definition

Searching finds whether an element exists in the array list.

Use Case

Searching a contact name in a phonebook.

C++ Example (Searching)

#include <iostream>
using namespace std;

int main() {
    int arr[] = {10, 20, 30, 40};
    int key = 30;

    for(int i = 0; i < 4; i++) {
        if(arr[i] == key) {
            cout << "Element found at index " << i;
            return 0;
        }
    }
    cout << "Element not found";
    return 0;
}

6.5 Updating Operation

Definition

Updating modifies an existing element in the array list.

Use Case

Updating a product price in inventory.

C++ Example (Updating)

#include <iostream>
using namespace std;

int main() {
    int arr[] = {10, 20, 30};
    arr[1] = 25;

    for(int i = 0; i < 3; i++)
        cout << arr[i] << " ";

    return 0;
}

. Real-World Use Cases of Array List

• Dynamic menus in applications

• Online booking systems

• Student record management

• Game score tracking

• E-commerce platforms

8. Implementation of Array List in C++ (Using Class)

#include <iostream>
using namespace std;

class ArrayList {
    int arr[10];
    int size;

    public:
    ArrayList() {
        size = 0;
    }

    void add(int value) {
        arr[size++] = value;
    }

    void display() {
        for(int i = 0; i < size; i++)
            cout << arr[i] << " ";
    }
};

int main() {
    ArrayList list;
    list.add(10);
    list.add(20);
    list.add(30);
    list.display();
    return 0;
}

9. Advantages and Limitations

Advantages

• Dynamic size

• Fast access using index

• Easy to implement

Limitations

• Shifting elements is costly

• Fixed capacity in basic implementation

• Memory reallocation overhead

10. Conclusion

An Array List is one of the most useful dynamic data structures in programming. It combines the speed of arrays with the flexibility of dynamic memory allocation. Understanding its operations—insertion, deletion, traversal, searching, and updating—is essential for building efficient and scalable software applications.

Mastering array lists builds a strong foundation for advanced data structures and algorithms.

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