Chapter 48 - Thinking Ahead

Question 1

What does thinking ahead lets us establish? all of them

Answer 1

Things necessary before starting development of software.

Question 2

What is an input?

Answer 2

information relevant and necessary for the problem to be solved.

Question 3

What is an output?

Answer 3

Solution/results to the problem

Question 4

What are the benefits of identifying inputs?

Answer 4

We can see where the information is coming from, the format it is in, how we can get it where we need it and how to use it for the most optimal solution.

Question 5

What are the benefits of identifying outputs?

Answer 5

We are able to determine processing stages required to transform inputs into what we want.

Question 6

What are the possible inputs to a touchscreen navigation system?

Answer 6

Coordinates
Destination
Settings
location (GPS does it automatically)

Question 7

What are the possible outputs of a touchscreen navigation system?

Answer 7

Map
Directions
Audio
Time and route estimates

Question 8

What does thinking ahead involve?

Answer 8

Identifying inputs
Identifying outputs
Caching
Identifying reusable program components

Question 9

What is the concept of caching in thinking ahead?

Answer 9

Using it in order to speed up retrieval of information, it prepares data before it is needed

Question 10

What is a precondition?

Answer 10

A condition that must be true or correct prior to execution of program/procedure/subprocedure

Question 11

Why are preconditions added?

Answer 11

To ensure values are initialised correctly, so that program operation is correct and solution operates as expected

Question 12

What are the advantages of having preconditions?

Answer 12

• The programmer/tester knows what checks must be made before a routine is entered where those conditions are used
• Helps to make code more reusable, so less coding required
• Easier to debug and maintain program

Question 13

What is a program library?

Answer 13

series of predefined and compiled routines that are available for use in programs

Question 14

Why do programmers and companies often use program libraries?

Answer 14

As it is impractical to start everything from scratch. Code will be simpler,easier and quicker to produce,easier to maintain,easier to read and understand.

Question 15

Give some examples of program libraries

Answer 15

Windows DLL (dynamic link library) 
Python import modules 
C Library - using #include

Question 16

What should we think about when developing a routine in a program?

Answer 16

Whether it can be reused in the same program or be useful in future ones.

Question 17

What is cache memory?

Answer 17

High performance memory that stores frequently used data and information.

Question 18

What does implementing cache memory mean?

Answer 18

The rate of execution of programs is very quick. Also it is done automatically by OS.

Question 19

What are the benefits of having cache memory?

Answer 19

• Speeds up program execution and throughput
• Reduces load on server or memory
• Increase in performance of processing data (especially effective in a server as it is less reliant on reliable connection)

Question 20

Why is caching in this topic?

Answer 20

It is a prime example of how thinking ahead is implemented into computer science,as data is ready prior to when it is needed.

Question 21

What can be used with cache memory. What is this process and how does work?

Answer 21

Prefetching , when CPU requests data to be placed in cache before it is necessary

Question 22

What is a downside of prefetching?

Answer 22

It requires very complex algorithms that determine the likelihood of data to be used in the near future.

Question 23

What is an upside to prefetching?

Answer 23

Data in cache is more likely to be useful and rate of program execution therefore increases.

Question 24

What are the drawbacks of cache memory?

Answer 24

• Increases maintenance costs if applicable

- Expensive, increases development costs

Question 25

In programming what are often the preconditions?

Answer 25

The parameters and variables