1. OOP Details Constructors, copies, access

2. Initialize Fields are not initialized by default:

3. Initialize C++11 allows initialization of members

4. Constructor Constructor : special function that initializes an object – No return type – Function name is same as class name – Job: initialize ALL member variables

5. Default Constructor Default Constructor : has no arguments – Called when you create an object like: – Can NOT be called with parens!!!

6. Customizing Default Constructor Default constructor provided, but useless – Does not initialize anything Define it yourself to initialize member variables:

7. Parameterized Constructors Constructors can have parameters: Use parens after object name to pass:

8. Overloaded Constructors can be overloaded – Selected based on provided parameters

9. Gotcha If you define constructors… Default constructor does not exist:

10. Rules of Thumb Always write constructors – At least default Each constructor should initialize every member variable

11. Modern Construction C++11 added member initialization in declaration: Old C++New C++

12. Why is this bad?

14. Avoid Redundancy If you are representing the same data in more than one place you may be doing it wrong… – Favor calculating over storing

15. Encapsulation & Information Hiding Two big ideas in OOP – Encapsulation : Grouping behaviors with data – Information Hiding : Limiting access to (messy) details of an object

16. Why Hide Details Abstraction is the only way to understand complex systems Want leak proof abstractions – How does clock represent the time internally? Who cares!

17. Private vs Public private & public : access specifiers – public: accessible anywhere – private: only accessible inside the class

18. Private vs Public Compile error to access private data:

19. Private vs Public Rule of thumb: – State (variables) private – Behaviors public

20. Accessing Private Data Accessors return value of private data:

21. Accessing Private Data Mutators allow modification of private data:

22. = Copies Members Assignment operator copies members c1 radius: 5 X: 0 Y: 0 c2 radius: 5 X: 0 Y: 0

23. = Copies Members Objects are distinct after that point: c1 radius: 5 X: 2 Y: 3 c2 radius: 5 X: 0 Y: 0

24. Other Operators = and. are only operators that work on objects automatically – No ==, etc… Can overload others…later

25. Anonymous Objects Constructor call on Classname() produces anonymous object: ???? radius: 5 X: 0 Y: 0

26. Anonymous Objects Constructor call on Classname() produces anonymous object: ???? radius: 5 X: 0 Y: 0