1. Chapter 2 Objects and Classes
Bernard Chen
Spring 2006

2. 2.1 What is OO programming?
Object: an atomic unit that has structure and state
Information hiding: Black-box analogy
Encapsulation: grouping of data and functions
Inheritance: mechanism allows extending functionality of an object.

3. How does C++ support OO Template: the logic is independent of the type
Inheritance
Polymorphism: allows us to implement
new types (classes) that
share same logic

4. 2.2 Basic Class Syntax
Class members: either data or functions and categorized into either public, protected,or private.
Public: visible to an instance of (object) a class
Private: visible only inside an instance of a class
Protected: similar to private but visible to derived classes.
Default: all members are private

5. Constructors
Member functions that describe how an object is declared and initialized.
If no constructor defined, compilers will generate one called default constructor.
Explicit constructors prevent automatic type conversion.

6. Constant Member Function
Constant functions (accessors) : functions that do not change any data member.
const is a part of the function signature. [const] return_type name([const] parameter_list) [const];
Interface: describes what can be done to the object, i.e. the header.
Implementation: represents internal processes specified by the interface.

8. Big three: Destructor, Copy Constructor, and Operator =
•Destructor tells how an object is destroyed and freesdresources when it exists scope.
~IntCell();
•Copy Constructor allows a new object construct using the data in an existing one.
IntCella(5); // a new IntCellcall a
IntCellb(a); // another IntCellcall b
•Operator = copy assignment, copies data members using = by default.=> may cause shallow copying.

9. This (predefine pointer)

10. 2.3 Additional C++ Features
Operator overloading: extending the types to which an operator can be applied.
example: string x=“Mary’s score is:”;
int y=95;
string z=x+y;
“.”, “.*”, “?:”, “sizeof” can’t be overloaded

11. Additional C++ Features
Type conversion creates a temporary object of a new type–
Example: int a = 5;
double b = a; //implicit cast

12. 2.5 Exceptions (report error)
An object that stores information transmitted outside the normal return sequence and is used to signal exceptional occurrences
Handle exceptions by throw and catch clauses.

13. Exceptions example try { for (intn=0; n<=10; n++)
if (n>9) throw "Out of range"; }
} catch (char * str)
cout<< "Exception: " << str<< endl;

14. 2.6 String Class C string: array of character terminated by ‘\0’
C++ standard string: a STL class with all overload operators and built-in functions

16. Summary Construction/ destruction of objects Copy semantics
Overloading
Implicit/explicit type conversion
Information hiding/atomicity