Key Things

Question 1

What are the principles of OOP?

Answer 1

• Information / data hiding
• Encapsulation
• Abstraction
• Modularization

Question 2

Encapsulation goes hand-in-hand with what?
What about modularization?

Answer 2

Encapsulation goes hand-in-hand with information hiding.
Modularization with low coupling and high cohesion

Question 3

What are the basic elements of a C++ program?

Answer 3

Classes, methods, and data members

Question 4

How are these different:
#define constant
const constant
constexpr constant

Answer 4

define constant - preprocessor definition that does a simple replacement during preprocessing and before compiling

const constant - names constant declaration where the programmer commits to not changing a value

constexpr constant - constant expressions evaluated at compile time, allowing them to be places in read-only memory

Question 5

What is the difference in visibility between a struct and a class?

Answer 5

struct - default public
class - default private

Question 6

In what ways are things allocated on the heap?

Answer 6

By using the malloc() function or using ‘new’

Question 7

What are the advantages and disadvantages C++ having no garbage collection?

Answer 7

Advantages: performance

Disadvantages: cumbersome, error-prone, memory leaks, painful

Question 8

Can void pointers be dereferenced using “*”?

Answer 8

No

Question 9

Functions must be ___ before they are ____?

Answer 9

Functions must be declared before they are called

Question 10

How does C++ allow for pass by reference?

Answer 10

By supplying the ‘&’ in front of the parameter:

void Two (int& x) {
x = 2;
cout &laquo_space;x &laquo_space;endl;
}

Question 11

Why is it poor-form to use the ‘declaring namespace’ syntax in a header file?

Answer 11

Because it can lead to inadvertently opening up access to namespaces in unanticipated ways, leading to name collisions and other problems

Question 12

Classes are an expanded concept of what?

Answer 12

Structs

Question 13

What are private, public, and protected access specifiers for class members?

Answer 13

private - accessible only from within other members of the same class

public - accessible from anywhere where the class and its instantiated objects are visible

protected - accessible from other members of the same class and members of their derived class

Question 14

What is the difference between the following two:

ObjectType *obj1;
ObjectType obj2;

Answer 14

obj1 is a pointer and therefore not instantiated without calling the ‘new ObjectType’ on it.

obj2 is instantiated

Question 15

If an access specifier is not provided when inheriting from a base class, what is the default?

Answer 15

private

Question 16

What are public, protected, and private inheritance?

Answer 16

public inheritance - all members are inherited with the same access levels as they had in the base class

protected inheritance - all public members in the base class are inherited as protected

private inheritance - all members in the base class are inherited as private

Question 17

What is the difference between having the ‘virtual’ keyword on a function and not having it?

Answer 17

If there is a ‘virtual’ keyword attached to a method, then when there is some kind of subtype polymorphism such as:

Person *p;
Student *s = new Student();
s->sayHello();
p = s;
p->sayHello();

When p->sayHello() is executed, it calls the method from the student class, not the person class

If there were to be no ‘virtual’ keyword, then the line p->sayHello() would execute the method from the person class.

Question 18

Where is ‘virtual’ specified?

Answer 18

In the header file

Question 19

What does it mean for a derived class to be concrete?

Answer 19

All virtual methods are implemented

Question 20

What is a “fat interface”?

Answer 20

It has many responsibilities and is unfocused and hard to understand/modify