Stack Array Base

#include <iostream>
#define size 10

class Stack
{
private:
    int top1;
    int top2;

public:
    int stack1[size];
    int stack2[size];

    Stack() { top1 = -1, top2 = -1; }

    bool isFull()
    {
        return (top1 >= (size - 1)) ? true : false;
    }

    bool isEmpty()
    {
        return (top1 < 0) ? true : false;
    }

    void push(int val)
    {
        if (!isFull())
        {
            stack1[++top1] = val;
            std::cout << "Data " << val << "  successfuly pushed\n";
        }

        else
            std::cout << "Stack overflow!!\n";
    }

    int pop()
    {
        if (top1 < 0)
        {
            std::cout << "Stack underflow!!\n";
            return 0;
        }

        else
        {
            int data = stack1[top1--];
            return data;
        }
    }

    int peek()
    {
        if (top1 < 0)
        {
            std::cout << "Stack is empty!!";
            return 0;
        }

        else
        {
            int data = stack1[top1];
            return data;
        }
    }

    void printStack()
    {
        int listLength = sizeof(stack1) / sizeof(stack1[0]);
        std::cout << "Content: ";
        for (int i = 0; i < listLength; i++)
            std::cout << stack1[i] << ", ";
    }
};

void sortStack()
{
    Stack stack;
    int i = 0;
    int stackSize = sizeof(stack.stack1) / sizeof(stack.stack1[0]);
    while (i < stackSize)
    {
        //if()
    }
}

int main()
{
    int dataSet[] = { 12, 76, 45, 34, 6, 13, 21, 5, 10, 89 };
    int dataSetLength = sizeof(dataSet) / sizeof(dataSet[0]);
    Stack stack;

    for (int i = 0; i < dataSetLength; i++)
    {
        stack.push(dataSet[i]);
    }
    int peekTop = stack.peek();
    std::cout << "Top: " << peekTop << "\n";
    stack.printStack();

    return 0;
}