/* 4. Write a C++ program to create a class called as STACK using array of integers. Implement the following operations by overloading the operators + and --. Also display the status and contents of the stack after each operation by overloading the operator <<.
(i) s1=s1+element; where s1 is a object of the class STACK and element is an
integer to be pushed on top of the stack.
(ii)s1=s1--; where s1 is a object of the STACK, -- operator pops the element.
Handle the STACK empty and STACK full conditions. */

#include<iostream.h>
#include<stdlib.h>
#include<conio.h>
#define MAX 5
class STACK 

{
    int top,a[MAX];

    public:
        STACK()
        {
            top = -1;
        }
        STACK operator +(int element);
        STACK operator --();
        friend ostream& operator <<(ostream& Out,STACK s);
};
STACK STACK::operator +(int item)
{
    if (top >= MAX-1)
        cout<<"\nERROR : Stack Overflow";
    else
        a[++top] = item;
    return (*this);
}
STACK STACK::operator --()
{
    if (top < 0)
        cout<<"\nERROR : Stack Underflow";
    else
        cout<<"\nPopped item is "<<a[top--];
    return (*this);
}
ostream& operator <<(ostream& Out,STACK s)
{
    if (s.top == -1)
        Out<<"\nERROR : Stack is empty";
    else
    {
        Out<<"\nStack contents is as follows :\n";
        for (int i=s.top; i>=0; i--)
        Out<<s.a[i]<<endl;
    }
    return Out;
}
void main()
{
    STACK s1;
    int ch,element;
    clrscr();
    while(1)
    {
        cout<<"\nMENU\n1. Push\n2. Pop\n3. Display\n4. Exit\nYour Choice = ? ";
        cin>>ch;
        switch(ch)
        {
            case 1:
                cout<<"\nEnter element to be pushed on to the stack : ";
                cin>>element;
                s1 = s1 + element;
                break;

            case 2:
                s1 = s1--;
                break;

            case 3:
                cout<<s1;
                break;

            case 4:
                exit(0);

            default:
                cout<<"\nInvalid Choice. Try again";
        }
    }
    getch();
}