2.3 Programming Robust Programs

Question 1

Define defensive design

Answer 1

Defensive design helps to ensure programs function properly. This means that programs should never break or produce errors.

Question 2

Define anticipating misuse

Answer 2

Anticipating misuse involves thinking ahead about how users might misuse the program. They will then design the program to prevent this happening. Preventing too many entries of a
password to make it harder for hackers to guess

Question 3

Define authentication

Answer 3

Authentication can confirm the identity of a user before they’re allowed to access particular data or programs.

Question 4

Define input validation

Answer 4

Input validation is checking that the data meet certain criteria before passing it into the program e.g. checking that an email address contains an @ symbol.

Question 5

Define maintainability

Answer 5

Well maintained programs make it easy for other programmers to understand your code. This can include using sub programs, comments, indent, clear naming.

Question 6

Define syntax error

Answer 6

When the compiler or interpreter does not understand something you have typed, because it does not follow the rules or grammar of the programming language.

Question 7

Define logic error

Answer 7

When the compiler or interpreter is able to run the program, but the program does something unexpected.

Question 8

Define iterative testing

Answer 8

The program is tested while it is being developed. Often a programmer will test a module, fix any errors and then test it again.

Question 9

Define final testing

Answer 9

Final testing – the program is tested at the end of the development process. The whole program is tested at the same time to check it is all working.

Question 10

Define test plan

Answer 10

The test plan will outline exactly what you are going to test and how you are going to test it. Good test plan will anticipate all potential issues with the program

Question 11

Define normal data

Answer 11

Data that the user is likely to input into the program.

Question 12

Define boundary data

Answer 12

Values at the limit of what the program should be able to handle.

Question 13

Define invalid data

Answer 13

Inputs with the correct data type that should be rejected by the program.

Question 14

Define erroneous data

Answer 14

Inputs with an incorrect data type that should be rejected by the program.

Question 15

Range check

Answer 15

A number or date is within a sensible or allowed range

Question 16

Type check

Answer 16

Data is of the right type e.g integer

Question 17

Length check

Answer 17

Text entered is not too long or too short

Question 18

Presence check

Answer 18

Checks that data has been entered

Question 19

Format check

Answer 19

Checks that the format is correct e.g email address or postcode

Question 20

What is validation?

Answer 20

Ensures data entered is sensible, reasonable and allowed

Question 21

What is verification?

Answer 21

Double checks that the data has been entered correctly

Question 22

Password routines

Answer 22

Once an ID and password has been entered it is looked up in a database. If the ID cannot be found, an error message is displayed.

Question 23

Why are programs maintained?

Answer 23

Improve code, add new features, fix bugs

Question 24

What makes a program maintainable?

Answer 24

Sub programs
Appropriate naming conventions
Indentation
Commenting

Question 25

Why are sub programs used?

Answer 25

Take inputs and return a necessary value, allowing them to be reused multiple times within the main program. They include functions and procedures.

Question 26

Why are appropriate naming conventions important?

Answer 26

Makes the code easier to read and understand, includes appropriately named functions, procedures, variables and constants.

Question 27

Why is indentation important?

Answer 27

Helps to see which lines of code are part of which structure

Question 28

Why are comments important?

Answer 28

Helps other programmers to easily understand what is going on in the code

Question 29

What are comments usually written for?

Answer 29

Parts of a program or algorithm that are difficult to understand, at the start of a function or procedure,

Question 30

What are comments not usually written for?

Answer 30

Every line, to explain obvious parts of code, to explain syntax

Question 31

Verification

Answer 31

Checking whether data has been entered correctly e.g double entry

Question 32

Input sanitisation

Answer 32

Cleaning up data that has been input

Question 33

Validation

Answer 33

Checking whether input data follows criteria

Question 34

Maintainable code

Answer 34

Allowing other programmers to understand the code

Question 35

Lookup table

Answer 35

A table of acceptable entries