C++ extends the variable declaration syntax from built-in types (e.g., int

i;) to objects of user-defined types. The syntax is the same: TypeName VariableName.

For example, if the header file “Car.hpp” defines a user-defined type called Car,

objects (variables) of class (type) Car can be created:

#include "Car.hpp" // Define class Car

void f()

{

Car a; // 1: Create an object

a.startEngine(); // 2: Call a member function

a.tuneRadioTo("AM", 770); // 3: Call another member function

} // 4. Destroy the object

int main()

{

f();

}

When control flows over the line labeled 1: Create an object, the runtime

system creates a local (auto) object of class Car. The object is called a and can

be accessed from the point where it is created to the } labeled 4: Destroy the

object.

When control flows over the line labeled 2: Call a member function, the

startEngine() member function (a.k.a. method) is called for object a. The

compiler knows that a is of class Car so there is no need to indicate that the

proper startEngine() member function is the one from the Car class. For

example, there could be other classes that also have a startEngine() member

function (Airplane, LawnMower, and so on), but the compiler will never get

confused and call a member function from the wrong class.