8.2 Defensive design

Question 1

What is data validation?

Answer 1

A routine that ensures that data entered is of the right types - for example an integer

Question 2

Give the different types of validation checks

Answer 2

Range check, type check, length check, presence check, format check

Question 3

Range check

Answer 3

A number or date is within a sensible/ allowed range

Question 4

Type check

Answer 4

Data is of the right type

Question 5

Length check

Answer 5

Text entered is not too long or too short

Question 6

Presence check

Answer 6

Checks that data has been entered

Question 7

Format check

Answer 7

Checks that the format of the input is correct

Question 8

Difference between Validation and verification

Answer 8

Validation can only check that data entered is reasonable. Verification is used to double-check that the data has been typed in correctly

Question 9

Authentication routines

Answer 9

Authentication routines are used to make sure a person is who they claim to be

Question 10

Why should you maintain programs?

Answer 10

To improve code, fix bugs or add new features to the program

Question 11

What can you do with your code to improve maintability?

Answer 11

Subprograms, using appropriate naming conventions, indentation and commenting

Question 12

Give examples of subprograms

Answer 12

Functions and procesdures

Question 13

What are comments usually written for

Answer 13

Parts of a program that are difficult to understand. At the start of a function or procedure to explain what it does

Question 14

When to not use comments

Answer 14

Every line of code. To explain parts that are obvious. To explain syntax used in the programming language