C++ Dynamic Memory Allocation: Stack implementation with memory allocation

Last update on December 20 2024 12:22:42 (UTC/GMT +8 hours)

Write a C++ program to dynamically allocate memory for a stack data structure. Implement push and pop operations on this stack.

Sample Solution:

C Code:

#include <iostream> // Including the Input/Output Stream Library

class Stack {
  private:
    int * array; // Dynamic array to store the stack elements
    int top; // Index of the top element
    int capacity; // Maximum capacity of the stack

  public:
    // Constructor to initialize the stack with a given size
    Stack(int size) {
      capacity = size;
      array = new int[capacity]; // Allocate memory for the stack
      top = -1; // Initialize top as -1 to indicate an empty stack
    }

    // Destructor to deallocate memory when the object is destroyed
    ~Stack() {
      delete[] array; // Free the dynamically allocated memory for the stack
    }

    // Function to push an element onto the stack
    void push(int value) {
      if (top == capacity - 1) { // Check for stack overflow
        std::cout << "Stack Overflow. Cannot push element: " << value << std::endl;
        return;
      }
      array[++top] = value; // Increment top and add the element to the stack
      std::cout << "Pushed element: " << value << std::endl; // Print the pushed element
    }

    // Function to pop an element from the stack
    void pop() {
      if (top == -1) { // Check for stack underflow
        std::cout << "Stack Underflow. Cannot pop from an empty stack." << std::endl;
        return;
      }
      int value = array[top--]; // Get the top element and decrement top
      std::cout << "Popped element: " << value << std::endl; // Print the popped element
    }
};

int main() {
  int size = 5; // Size of the stack
  std::cout << "Size of the stack: " << size << "\n" << std::endl; // Print the stack size
  Stack stack(size); // Create an instance of the Stack class with the specified size

  // Push elements onto the stack
  stack.push(1);
  stack.push(2);
  stack.push(3);
  stack.push(4);
  stack.push(5);

  // Pop elements from the stack
  std::cout << "\nPopped 6 elements from the above stack:" << std::endl;
  stack.pop();
  stack.pop();
  stack.pop();
  stack.pop();
  stack.pop();
  stack.pop(); // Attempting to pop from an empty stack

  return 0; // Returning 0 to indicate successful execution of the program
}

Sample Output:

Size of the stack: 5

Pushed element: 1
Pushed element: 2
Pushed element: 3
Pushed element: 4
Pushed element: 5

Popped 6 elements from the above stack:
Popped element: 5
Popped element: 4
Popped element: 3
Popped element: 2
Popped element: 1
Stack Underflow. Cannot pop from an empty stack.

Explanation:

In the above exercise,

push(): This function adds elements to the stack. It checks if the stack is already full (top == capacity - 1). If it is, it displays an error message indicating a stack overflow. Otherwise, it increments the top index and assigns the provided value to the corresponding position in the array.

pop(): This function removes elements from the stack. It checks if the stack is empty (top == -1). If it is, it displays an error message indicating a stack underflow. Otherwise, it retrieves the value from the top position in the array, decrements the top index, and displays the popped element.

Flowchart:

CPP Code Editor:

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