Declarations and Definitions
Exploration 20 introduced the distinction between declarations and definitions. This is a good time to remind you of the difference and to explore declarations and definitions of classes and their members.
Declaration vs. Definition
Recall that a declaration furnishes the compiler with the basic information it needs, so that you can use a name in a program. In particular, a function declaration tells the compiler about the function’s name, return type, parameter types, and modifiers, such as const and override.
A definition is a particular kind of declaration that also provides the full implementation ...