c++ program for implementation of stack operations using arrays

#include<iostream.h>

STACK OPERATIONS

#include<conio.h>
class stack
{
int top,st[20];
public:
stack()
{
top=-1;
}
void push(int a)
{
st[++top]=a;
}
int pop()
{
return st[top--];
}
void display();
};
void stack::display()           //inline function
{
 for(int i=top;i>=0;i--)
 {
 cout<<"\n"<<st[i];
 }
}
void main()
{
 stack s;
 int a,z,data,x;
 clrscr();
 do
 {
 cout<<"1.push 2.pop 3.display:";
 cin>>a;
 switch(a)
 {
 case 1:cout<<"enter the data to push.";
cin>>data;
s.push(data);break;
 case 2:x=s.pop();
 cout<<"popped element is:"<<x;break;
 case 3:s.display();
 }
 cout<<"continue 1.yes 2.no";
 cin>>z;
 }while(z!=2);
 getch();
}