task2b

#include <stdlib.h>
#include <iostream>
#include "stack.h"

using namespace std;

stack::stack()
{
  //  this->top=0;
    this->data = (int*)malloc(sizeof(int) * 2);
    if(this->data == NULL)
    {
        cout << "unable to allocate memory" << endl;
        exit(1);
    }
    this->top=-1;
    this->size=2;
}
stack::~stack()
{
    free(this-> data);
}

bool stack::isEmpty()
{
    if(this->top == -1)
    {
        return true;
    }
    else
    {
        return false;
    }
}

void stack::push(int element)
{
    int *temp = (int*)malloc(sizeof(int) * this->size * 2);
        if (temp == NULL)
        {
            cout <<"unable to allocate" << endl;
            return;
        }
        int i=0;
        for(i = 0; i<= this ->top; i++)
        {
            temp[i] = this->data[i];
        }
        free(this->data);
        this->data = temp;
        this-> size *=2;
    this-> data[++this->top] = element;
}

int stack::pop()
{
    if(isEmpty())
    {
        cout << "stack is empty" << endl;
        free(this->data);
        exit(-1);
    }
    else
    {
        return this->data[this->top--];
    }
}

stack::stack(const stack &s)
{
    this->data = (int*)malloc(sizeof(int) * s.size);
    if(this->data == NULL)
    {
        printf("unable to allocate memory");
        exit(1);
    }
    this->top=s.top;
    this->size=s.size;
    for(int i = this->top; i>=0;i--)
    {
        this->data[i] = s.data[i];
    }
}


stack & stack::operator= (const stack & s)
{
  if(this->size != s.size)
    {
        this->data = (int*)realloc(this->data, sizeof(int) * (s.size));
    }

    this->top=s.top;
    this->size=s.size;
    for(int i = s.top; i>=0;i--)
    {
        this->data[i] = s.data[i];
    }
    return *this;
}
void stack::display()
{
      for(int i =this->top; i>=0; i--)
    {
        printf(" %d ", this->data[i]);
    }
    printf("\n");
}