2.1.1

Question 1

Abstraction

Answer 1

• Removing unnecessary detail.
• Representing the key elements of the problem.

-Must consider what information is actually
relevant to the problem at hand.

• Complex problems can be split into several layers of abstraction.
• Higher layers are closer to the user, possibly providing a user interface.
• Lower levels interact with the computer.

Question 2

The Need for Abstraction

Answer 2

• Allows those who are not experts in a field to use systems by hiding more complex information which is irrelevant to using the system.
• Allows more efficient design by encouraging focus on the core elements of a problem.
• Reduces the time spent on a project.
• Prevents a project becoming too large or complex.
• Low-level programming languages directly interact with hardware but are hard to write so high-level languages abstract the machine code that is executed when a program is run.
• The TCP/IP model is an example of abstraction in networking.

Question 3

Abstraction and Reality

Answer 3

• Abstraction is more simplified than reality.
• Real world items are simplified into computer structures such as a table, variable or database.
• Objects used in object oriented programming can be an abstraction of real world entities.
• Attributes can represent the characteristics of a real world object.
• Methods can represent the actions a real world object may perform.

Question 4

Creating an Abstraction Model

Answer 4

• What problem needs to be solved?
• Who will use the model?
• How will the model be used?
• Which are the key elements of the problem for the people using the model and how they will use it?

Question 5

Procedural Abstraction

Answer 5

• Allows a programmer to use a function without understanding the detail of its implementation.
• Used with data structures and in decomposition.
• Models the purpose of a subroutine without considering how it does what it does.

Question 6

Abstraction by Generalisation

Answer 6

• Similar elements of a problem may be
  grouped together.
• This allows common problems to be categorised.
• They can then be solved with a common solution.

Question 7

Procedural Abstraction

Answer 7

• Allows a programmer to use a function without understanding the detail of its implementation.
• Used with data structures and in decomposition.
• Models the purpose of a subroutine without considering how it does what it does.

Question 8

Data Abstraction

Answer 8

• Programmers may use complex data structures without needing to understand how they are implemented in detail.
• How data is being stored and filtered.