2.1.2

Question 1

What is the purpose of thinking ahead?

Answer 1

To make programs easy and intuitive for users to use

Question 2

What things do programmers need to consider when thinking ahead?

Answer 2

• Method of input/output
• Data structures used
• Data types used
• Order of data

Question 3

What are preconditions?

Answer 3

Requirements which must be met before a program can be executed

Question 4

Define caching

Answer 4

The process of storing instructions or values in cache memory after they have been used, as they may be used again

Question 5

How is caching used in storing web pages?

Answer 5

Web pages that a user frequently accesses are cached so the next time one of these pages is accessed, content can be loaded without delay

Question 6

What are the advantages of caching web pages

Answer 6

• Content can be loaded without delay
• Images and text do not have to be downloaded again multiple times
• Frees bandwidth for other tasks
• Less time spent waiting

Question 7

An algorithm predicts which instructions are likely to be used soon

Answer 7

Prefetching

Question 8

Limitations of caching

Answer 8

• Accuracy of the algorithms used
• Effectiveness of the algorithm in managing the cache
• Size of the cache

Question 9

Advantages of using reusable program components

Answer 9

• More reliable than new components as they have already been tested
• As developing from scratch isn’t necessary it saves time, money and resources

Question 10

Examples of reusable program components

Answer 10

• Abstract data structures (queues and stacks)
• Classes
• Subroutines