Key Points

Recap Video

There was a fair amount to digest in this lesson. As a review, and because sometimes it's helpful to see things presented a different way, here's a video that goes over what we've covered in this lesson. If you feel like you've already mastered the material, you can skip it.

Key Points

• Classes are conceptually similar to what you've seen before, but have syntactic/terminological differences.
• Instead of “instance variables” and “methods” we say “member variables” or “data members” and “member functions” (“members” to refer to them all together).
• Declarations/definitions
  • The class definition goes in the header file (.hpp). It declares all of the class members.
    • In CS 70 convention we name all member variables with a trailing underscore (e.g., age_).
  • The member-function definitions go in the source file (.cpp). They specify the instructions for each function.
  • When we define a member function we have to specify which class it belongs to using the scope-resolution operator (::):
    • For example, void Cow::moo(int numMoos);.
• A member function can be declared const.
  • A const member function promises not to change the values of member variables.
  • If you have a const object, you can only call const member functions on it.
• We looked at two different kinds of constructors:
  1. Parameterized constructors take parameters and must be invoked explicitly (e.g., Cow bessie{3, 12}).
  2. Default constructors take no parameters and are implicitly invoked for default initialization (e.g., Sheep fluffy;).
• You can disable the use of a default constructor using the delete keyword (e.g., Cow() = delete;).
• In a constructor, the member-initialization list specifies how to initialize each member variable.
  • For example, Cow(int numSpots, int age) : numSpots_{numSpots}, age_{age}.
  • In CS 70, you must use a member-initialization list whenever possible. (The only exception is initializing a primitive array when you want a copy of another array—for that case, you need to loop over the elements of the array you're copying to populate your new array.)
• A class definition ends in a semicolon (;).
  • A class definition ends in a semicolon.
  • A class definition ends in a semicolon.

(When logged in, completion status appears here.)

Previous Page Next Page