C++ Stack Exercises: Check if the stack (using an array) is full

Last update on August 19 2025 05:36:41 (UTC/GMT +8 hours)

2. Check if the Array-Based Stack is Full

Write a C++ program to implement a stack using an array with push and pop operations. Check if the stack is full.

Test Data:
MAX_SIZE of the array: 5
Insert some elements onto the stack:
Stack elements: 1 2 5 6 9
Is the stack full? 1

Sample Solution:

C++ Code:

 #include <iostream>

using namespace std;

#define MAX_SIZE 5 // Maximum size of stack

class Stack {
private:
    int top; // Index of top element
    int arr[MAX_SIZE]; // Array to store elements

public:
    Stack() {
        top = -1; // Initialize top index to -1 (empty stack)
    }

    bool push(int x) {
        if (isFull()) {
            cout << "Stack overflow" << endl; // Display message if stack is full
            return false; // Return false to indicate failure in pushing element
        }
        arr[++top] = x; // Increment top index and add element to array
        return true; // Return true to indicate successful element addition
    }

    int pop() {
        if (isEmpty()) {
            cout << "Stack underflow" << endl; // Display message if stack is empty
            return 0; // Return 0 to indicate failure in popping element
        }
        return arr[top--]; // Return top element and decrement top index
    }

    int peek() {
        if (isEmpty()) {
            cout << "Stack is empty" << endl; // Display message if stack is empty
            return 0; // Return 0 to indicate failure in peeking element
        }
        return arr[top]; // Return top element without modifying top index
    }

    bool isEmpty() {
        return (top < 0); // Return true if stack is empty (top index is -1)
    }

    bool isFull() {
        return (top >= MAX_SIZE - 1); // Return true if stack is full (top index is equal to MAX_SIZE - 1)
    }

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

int main() {
    cout << "MAX_SIZE of the array: " << MAX_SIZE;
    // Initialize a stack 
    Stack s; 
    cout << "\nInsert some elements onto the stack:\n";
    s.push(9); 
    s.push(6);
    s.push(5);
    s.push(2);
    s.push(1);
    s.display(); // Display elements in the stack
    cout << "Is the stack full? " << s.isFull() << endl; // Check if the stack is full
    cout << "\nRemove an element from the stack! ";
    cout << s.pop(); // Pop an element from the stack
    s.display(); // Display elements in the stack
    cout << "Is the stack full? " << s.isFull() << endl; // Check if the stack is full
    cout << endl;
    return 0;
}

Sample Output:

MAX_SIZE of the array: 5
Insert some elements onto the stack:

Stack elements: 1 2 5 6 9
Is the stack full? 1

Remove an element from the stack! 1
Stack elements: 2 5 6 9
Is the stack full? 0

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to implement a stack using an array and include functionality to detect a full stack before insertion.
Develop a C++ program that simulates a fixed-size stack with an array and prints a warning message when a push is attempted on a full stack.
Design a C++ program to build a stack with an array and verify its full status dynamically during successive push operations.
Implement a C++ program to manage an array-based stack and check its full condition before each push, with clear output messages.

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