Simple Stack Implementation in C++

stack.cpp

#include <iostream>
using namespace std;
#define null 0

class StackArray {
private:
    int size;
    int *stackArr;
    int top;
    void resize() {
        int tempSize = size * 2;
        int *temp = new int[tempSize];
        for(int i = 0; i < size; i++) temp[i] = stackArr[i];
        delete[] stackArr;
        stackArr = temp;
        size = tempSize;
    }
public:
    StackArray(int size) {
        this->size = size;
        stackArr = new int[size];
        top = -1;
    }
    void push(int data) {
        if(top == size - 1) resize();
        stackArr[++top] = data;
    }
    void pop() {
        if(top != -1) top--;
    }
    void print() {
        for(int i = 0; i <= top; i++) {
            cout << stackArr[(top - i) % size] << endl;
        }
        cout << endl;
    }
    void test() {
        push(1);
        push(3);
        push(4);
        push(7);
        print();
        pop();
        print();
    }
    ~StackArray() {
        delete[] stackArr;
    }
};


class Node {
public:
    int data;
    Node *next;
    Node(int data) {
        this->data = data;
        next = null;
    }
};

class StackLinkedList {
private:
    Node *top;
public:
    StackLinkedList() {
        top = null;
    }
    void push(int data) {
        Node *n = new Node(data);
        if(top == null) top = n;
        else {
            n->next = top;
            top = n;
        }
    }
    void pop() {
        if(top != null) {
            Node *temp = top;
            top = top->next;
            delete(temp);
        }
    }
    void print() {
        Node *temp = top;
        while(temp != null) {
            cout << temp->data << endl;
            temp = temp->next;
        }
        cout << endl;
    }
    void test() {
        push(3);
        push(9);
        push(6);
        print();
        pop();
        print();
    }
    ~StackLinkedList() {
        Node *next;
        while(top != null) {
            next = top->next;
            delete(top);
            top = next;
        }
    }
};

int main() {
    cout << endl << "Array:" << endl;
    StackArray sArr(4);
    sArr.test();
    cout << endl << "Linked List:" << endl;
    StackLinkedList sll;
    sll.test();
    return 0;
}