#include <iostream.h>
using namespace std;

class Vehicle{
	protected:
	   int number;
	   double gas;
	public:
	   virtual void show()=0;   // pure virtual function
};

// derived class Car
class Car: public Vehicle{
	public:
	   Car(int n=1, double g=9.0);
	   void show();   // overriding function
};

// derived class Truck
class Truck: public Vehicle{
	public:
	   Truck(int n, double g);
	   void show();    // overriding function
};

int main()
{
        cout << "test of abstract class with pure virtual functions" << endl;
	//Vehicle myvehicle;   //this is not allowed
	Car mycar(23, 92.0);
	Truck mytrack(102,198.3);
	mycar.show();
	mytrack.show();
        return 0;
}

Car::Car(int n, double g)    // constructor with default argument
{
	number = n;
	gas=g; 
}  

Truck::Truck(int n, double g)
{
	number = n;
	gas=g; 
}

void Car::show()
{
	cout << "This is Car (number, gas) =" << number << ","  <<gas << endl;
}

void Truck::show()
{
	cout << "This is Truck (number, gas) =" << number << ","  <<gas << endl;
}