Lecture 1 Notes

Question 1

What is a program?

Answer 1

A list of instructions for a computer to execute.

Question 2

What are Machine Languages?

Answer 2

Languages used by the computer, but difficult for humans to read.

Question 3

What are assembly languages?

Answer 3

Symbolic translation of machine code which are easier for people to read (but still kind of hard)

Question 4

What are high-level procedural languages (such as Pascal, Fortran, and C)?

Answer 4

More human-readable languages that can be converted into assembly language and then assembled into machine code.

Question 5

What are Object-Oriented Languages (C++, Java, Smalltalk)?

Answer 5

Languages that encapsulate their data and procedures together in units called objects, which contain more than just functions. This makes the code more modular and readable to humans.

Question 6

What is the C programming language?

Answer 6

A high-level procedural programming language.

Question 7

What is the C++ language?

Answer 7

An object-oriented programming language based on the C programming language.

Question 8

What is an object?

Answer 8

An encapsulation of data and functions that act upon that data.

Question 9

What are the three aspects of an object?

Answer 9

• Name – The variable name given to the object.
• Attributes (member data) – The data that describes what the object is.
• Behavior (member functions) – behavior aspects of the object, aka functions that describe what the object actually does.

Question 10

What is a class?

Answer 10

A blueprint for objects.

A class is a user-defined type that describes what a certain type of object will look like. A class description consists of a declaration and a definition (usually split into separate files.)

An object is a single instance of a class.

Question 11

What’s the difference between a class and a struct?

Answer 11

They are essentially the same but with one key difference:

Structs have all their data and functions public by default, whereas Classes are private by default.

As a side note: Struct is still important for use in C++ because it is backwards compatible with C (which does not have Classes, but does have Structs.) C Structs can NOT contain functions, but C++ Structs can, so that’s important to know.

The use of a Struct or Class in your code is largely down to your personal style or preference since they are essentially interchangeable as far as functionality.

Question 12

What does DDU design stand for?

Answer 12

Declare, Define, Use

Question 13

What is the Declare portion of DDU design?

Answer 13

A declaration gives an interface.

A variable declaration gives the type.

A function declaration tells how to use the function (without any specifics on what it does.)

A class declaration shows what an object will look like and what its available functions area.

Implementation details are not needed for declarations.

Question 14

What is the Define portion of DDU design?

Answer 14

A definition usually consists of the implementation details. This isn’t necessary for the user of the interface to know. It’s essentially the code (or function body) of the function. A class definition consists of the definitions of its members.

Question 15

What is the Use portion of DDU design?

Answer 15

The use of an item through its interface.

The user of a function is a programmer who makes calls to the function without needing to know its implementation details.

The user of a class is a programmer who uses the class by creating objects and calling the available functions for those objects.

Question 16

What is the interface?

Answer 16

The interface is what the user sees.

The implementation details of the interface are often hidden in order to create a clear interface for the user, which is not necessarily the end user of a program. It could be a programmer, i.e. the user of a class.

Question 17

What does it mean when a member of a class has a public protection level?

Answer 17

The class member can be accessed from inside or outside of the object.

Question 18

What does it mean when a member of a class has a private protection level?

Answer 18

The class member can only be used by the object itself.

Question 19

What is the standard practice for protection level of a class’ member data?

Answer 19

Private

Question 20

What are the 4 reasons for making data private (data hiding)?

Answer 20

1. Makes the interface simpler for the user.
2. Principle of least privilege (need-to-know)
3. More secure. Less chance for misuse (accidental or malicious)
4. Class implementation is easy to change without affecting other modules that use it.

Question 21

What is the declaration format for a class?

Answer 21

class className
{
public:

private:
};