Constructor which haven't any argument or parameter called default constructor.
When class haven't any constructor compiler generate default constructor .
#include<iostream.h>
#include<conio.h>
class A{
	int x;
	int y;
	public:
		A(){
			x=5;
			y=6;
		}
		void display(){
			cout<<x<<" "<<y<<endl;
		}
};

void main(){
	A obj, obj1;
        clrscr();
	obj.display();
	obj1.display();
        getch();
}