2.3 Producing Robust Programs

Question 1

What is anticipating misuse?

Answer 1

Misuse of a program could be deliberate (a hacker trying to get into a system by making it crash) or accidental (a user forgetting their password)

Question 2

What is authentication?

Answer 2

The process of a user confirming that they are who they say they are

Question 3

Range check example

Answer 3

A number or date is within a sensible/allowed range

Question 4

Length check example

Answer 4

Text entered is not too long or too short e.g. between 8-15 characters

Question 5

Type check example

Answer 5

Data is of the right type e.g. integer

Question 6

Presence check example

Answer 6

Checks that data has been entered i.e. the field hasn’t been left blank

Question 7

Format check example

Answer 7

Checks that the format of, for example a postcode or email address, is correct

Question 8

What can validation do?

Answer 8

Check that data which has been entered is reasonable

Question 9

What is verification used for?

Answer 9

To double-check that data has been typed correctly (human errors)

Question 10

What are some features of subprograms?

Answer 10

• Written so that they can be reused multiple times in the program and easily transferred to others
• Makes debugging easier as it can be tested and edited separately

Question 11

What do naming conventions do?

Answer 11

Help to identify variable names by using meaningful and consistent format for them to aid readability

Question 12

What do indentations do?

Answer 12

Aid readability so it is clear where iterations and selections start and end

Question 13

What are some features of commenting?

Answer 13

• Help other programmers to understand your code
• Who wrote it, when and its purpose
• Comment complex coding sections and subroutines

Question 14

Why is testing needed?

Answer 14

To ensure the program functions as expected and meets all requirements. It should be destructive aiming not only to prove the function but also break it

Question 15

What is iterative testing?

Answer 15

• Tests modules and parts of the program for development
• Errors in each module need to be fixed before moving to the next
• Tests and retests subprograms separately

Question 16

what is final/terminal testing?

Answer 16

Tests the whole program

Question 17

What is a syntax error?

Answer 17

• The code written doesn’t conform to the rules of the language
• Will be flagged by translators
• The program cannot be run until all the syntax errors are fixed

Question 18

What is a logic error?

Answer 18

The program will run but not as intended

Question 19

What is normal data?

Answer 19

Typical data which the program is designed to handle

Question 20

What is boundary data?

Answer 20

Both ends of an allowed range e.g. 1-10 and just outside, 0 and 11

Question 21

What is invalid data?

Answer 21

Data of the correct type which should be rejected

Question 22

What is erroneous data?

Answer 22

Data of the incorrect type

Question 23

Why do we refine algorithms?

Answer 23

To make programs more efficient