146: Mainline

The following is a C++ definition of the box_car class; evidently, the chunks of memory that describe box cars hold values for three floating-point numbers—namely, height, width, and length:

class box_car { 
  public: 
    double height, width, length; 
}; 

Here is what each part of the definition does:

class            <-- Tells C++ that a class is to be defined 
      box_car    <-- Tells C++ the name of the class 
              {  <-- Marks the beginning of the body 
  public:        <-- Specifies where variables can be referenced 
    double ...;  <-- Introduces variables 
}                <-- Marks the end of the body 
 ;               <-- Marks the end of the class definition  

This definition of the box_car class describes height, width, and length variables only; no function definitions appear. Furthermore, this definition of the box_car class indicates, via the public: symbol, that all the variable values describing a box_car object will be available, and changeable, anywhere after the class named box_car has been defined.