1. Andy Wang Object Oriented Programming in C++ COP 3330
Test 1 Review
Andy Wang
Object Oriented Programming in C++
COP 3330

2. Exam Format Multiple choice True/false
Determine whether programming statements are legal
Declare and define member functions
Coverage: up to aggregation and composition

3. Class Basics Class Object A user defined type
A blueprint for building objects
Object
An instance of a class
With a name, member data, and member functions

4. DDU Design Model Declare (class declaration in the .h file)
Define (class members defined in the .cpp file)
Use (usage of class by building objects)

5. class Declaration vs. Definition
Similar in many aspects
Return types, member function names, number of parameters and types, keyword const
Exceptions
Declaration only
Keywords friend and explicit
Default parameter values
Definition only
Need scope resolution operator :: in definitions of member functions
The initialization list is only used in definitions
A member functions’ parameter names can differ in its declaration and definition

6. To Call Member Functions of an Object
Use the dot operator

7. Public vs. Private Can everything be public?
Who can access the private member data?
Member methods
Objects of the same class
Friend functions with the same class via object.member_data

8. Constructors Have no return type Have the same name as the class
Cannot be called directly as a member function
Called automatically
Default constructors
Have no parameters
Used when no other constructors exist

9. Conversion Constructor
A constructor that can be called with one parameter
Even with additional optional parameters
Converts the parameter type to the object type
Unless with the keyword explicit, conversion constructors are called automatically

10. Compilation Stages Compile stage Link stage Checks syntax and types
Matches member function calls with their declarations in the header files
Matches function calls to prototypes
Reports undeclared variables
Translates to .o files
Link stage
Matches function calls with their definitions
Checks for missing or duplicate definitions
Usually results in an executable

11. g++ Commands g++ -c frac.cpp g++ -o frac frac.o main.o
Compiles frac.cpp to frac.o
g++ -o frac frac.o main.o
Links frac.o and main.o to build a frac binary program

12. Misc Don’t include .cpp files
#include header files to satisfy “declare before use”
Debugging
Compilation errors (syntax with file and line numbers…)
Linker errors (undefined or multiply defined functions)
Runtime errors: fatal (crashes) and logical (bad results)

13. friend function Neither public nor private Not a member function
Definition has no scope resolution operator
Can access the private member data via object.private_member_data

14. Keyword const Can only be used for member functions of a class
Not for friend functions
Commonly used for accessor and display functions
Can disallow changes when passed by reference
Function(const int &a);
Can disallow member data of the calling object to be modified during a call
MemberFunction() const;

15. L-value vs. R-value L-value = r-value
Assigns the r-value to the l-value
x = 10 vs. 10 = x?
L-value can appear on the left-hand side of an assignment
Only an L-value can be passed by reference (without const)
R-value can appear on the right-hand side of an assignment

16. More on const const objects const member data static const member data
Can only call const member functions
Or, it won’t compile
const member data
Cannot be initialized in class declaration
Need to use an initialization list
static const member data
Can be initialized in class declaration
Cannot be changed afterwards
A single instance shared by all objects of the same class

17. Destructors Have no return type
Have same name as the class, with ~ in front
Only one destructor per class, provided by default
Does not take parameters
Called automatically when an object goes out of scope

18. Operator Overloading Cannot change a number of properties
Precedence
a + b*c
Associativity
(a + b) + c = a + (b + c)
Number of operands
Cannot create new operators
Can only overload existing ones
Cannot change the operator meaning on the built-in types
Can mix and match types (Fraction object + int object)

19. friend vs. Member Functions for Overloading
friend functions
Each takes two parameters for binary operators, one parameter for unary operators
Often needed for overloading the following operators
+, -, *, /, ==, !=, >=, <=, >, <, <<, >>, etc.
Otherwise, the first parameter can be a built-in type, which may not have the conversion constructor for the newly defined type
Member functions
Each takes one parameter for binary operators, no parameter for unary operators

20. Exceptions Postfix increment and decrement operators (++, --)
Need a dummy parameter of type int

21. Aggregation
Embed an object of one class type as member data of another class type
Composition
Embedded objects would typically not exist independent of the container object
“Has a” relationship
Need to use the initialization list to initialize the embedded objects