In the following program, the `tank_car`

class definition
includes a default constructor function that initializes the
member variables in particular `tank_car`

objects:

#includeconst double pi = 3.14159; class tank_car { public: double radius, length; // Default constructor: tank_car ( ) {radius = 3.5; length = 40.0;} // Volume function: double volume ( ) {return pi * radius * radius * length;} }; main ( ) { tank_car t; cout << "The volume of the tank car is " << t.volume ( ) << endl; } --- Result --- The volume of the tank car is 1539.38