C++ Stack Exercises: Implement a stack using a dynamic array with push, pop

C++ Stack: Exercise-20 with Solution

Write a C++ program to implement a stack using a dynamic array with push and pop operations. Find the top element of the stack and check if the stack is empty or not.

Test Data:
Input the size of the stack: Is the stack empty? Yes
Input some elements onto the stack:
Stack elements are: 9 7 5 3 1
Is the stack full? No

Sample Solution:

C++ Code:

#include <iostream>

using namespace std;

class Stack {
private:
	// Dynamic array to store elements
    int* arra;     
    int top;        // Index of top element
    int capacity;   // Maximum size of the stack
public:
    // Constructor to initialize the stack with a given size
    Stack(int size) {
        arra = new int[size]; // Allocate memory for the stack array
        top = -1;       // Initialize top index to -1 (empty stack)
        capacity = size; // Set the maximum capacity of the stack
    }

    // Function to push an element onto the stack
    bool push(int x) {
        if (isFull()) {
            cout << "Stack overflow" << endl; // Display overflow message if the stack is full
            return false;
        }
        // Add element to array by incrementing top index
        arra[++top] = x;
        return true;
    }

    // Function to pop an element from the stack
    int pop() {
        if (isEmpty()) {
            cout << "Stack underflow" << endl; // Display underflow message if the stack is empty
            return 0;
        }
        // Return the top element and decrement the index of the top element
        return arra[top--];
    }

    // Function to peek the top element of the stack without removing it
    int peek() {
        if (isEmpty()) {
            cout << "Stack is empty" << endl; // Display message if the stack is empty
            return 0;
        }
        // Return the top element without modifying the top index
        return arra[top];
    }

    // Function to check if the stack is empty
    bool isEmpty() {
	// Stack is empty if top index is -1
        return (top < 0);
    }

    // Function to check if the stack is full
    bool isFull() {
	// Stack is full if top index is equal to capacity - 1
        return (top >= capacity - 1);
    }

    // Function to display the elements of the stack
    void display() {
        if (top < 0) {
            cout << "Stack is empty" << endl; // Display message if the stack is empty
            return;
        }
        cout << "\nStack elements are: ";
        for (int i = top; i >= 0; i--)
            cout << arra[i] << " "; // Display the elements of the stack
        cout << endl;
    }
};

int main() {
    int size;
    cout << "Input the size of the stack: ";
    cin >> size; // Take input for the size of the stack
    Stack stk(size); // Create a stack of the given size
    cout << "Is the stack empty? " << (stk.isEmpty() ? "Yes" : "No") << endl; // Check if the stack is empty
    cout << "\nInput some elements onto the stack:";
    stk.push(1);
    stk.push(3);
    stk.push(5);
    stk.push(7);
    stk.push(9);
    stk.display(); // Display the elements of the stack
    cout << "Is the stack full? " << (stk.isFull() ? "Yes" : "No") << endl; // Check if the stack is full
    cout << "\nRemove two elements from the said stack:";
    stk.pop();
    stk.pop();
    stk.display(); // Display the updated elements of the stack
    cout << "\nTop element is " << stk.peek() << endl; // Display the top element of the stack
    return 0;
}

Sample Output:

Input the size of the stack: 8
Is the stack empty? Yes

Input some elements onto the stack:
Stack elements are: 9 7 5 3 1
Is the stack full? No

Remove two elements from the said stack:
Stack elements are: 5 3 1

Top element is 5

Flowchart:

CPP Code Editor:

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