Stack implementation as a class.

# include<iostream.h>
# include<process.h>
# include<conio.h>
# define SIZE 20

class stack
{
int a[SIZE];
int tos; // Top of Stack
public:
    stack();
    void push(int);
    int pop();
    int isempty();
    int isfull();
};
stack::stack()
{
tos=0; //Initialize Top of Stack
}

int stack::isempty()
{
return (tos==0?1:0);
}
int stack::isfull()
{
return (tos==SIZE?1:0);
}

void stack::push(int i)
{
if(!isfull())
{
a[tos]=i;
tos++;
}
else
{
 cerr<<"Stack overflow error !
Possible Data Loss !";
}
}
int stack::pop()
{
if(!isempty())
{
return(a[--tos]);
}
else
{
cerr<<"Stack is empty! What to pop...!";
}
return 0;
}

void main()
{
stack s;
int ch=1,num;
while(ch!=0)
{
    cout<<"Stack Operations Mani Menu
1.Push
2.Pop
3.IsEmpty
4.IsFull
0.Exit

";
    cin>>ch;
    switch(ch)
    {
    case 0:
        exit(1); //Normal Termination of Program
    case 1:
        cout<<"Enter the number to push";
        cin>>num;
        s.push(num);
        break;
    case 2:
        cout<<"Number popped from the stack is: "<<s.pop()<<endl;
        break;
    case 3:
        (s.isempty())?(cout<<"Stack is empty.
"):(cout<<"Stack is not empty.
");
        break;
    case 4:
        (s.isfull())?(cout<<"Stack is full.
"):(cout<<"Stack is not full.
");
        break;
    default:
        cout<<"Illegal Option.
Please try again
";
    }
}//end of while
getch();
}