Paper 2 - Design, Testing and IDE's

Question 1

Defensive Design:

Answer 1

Will never break or produce errors - Very difficult to achieve. Programmers anticipate how users may: misuse their program and prevent it; ensure their code is well maintained and reduce the number of errors in code through testing.

Question 2

Input Sanitation

Answer 2

Removing unwanted characters

Question 3

Input Validation

Answer 3

Checking if data meets certain criteria.

Question 4

Examples of input validation :

Answer 4

Range Check - Check data is within a specified range
Presence Check - Checks data has been entered
Check Digit - Checks numerical data has been entered
format check - Checks data is in correct format (E.g date)
Look-up Table Checks data against table of values
Length Check - Checks data is correct length

Question 5

Authentication

Answer 5

Confirms identity of user, allowing the access to data

Question 6

What is meant by Well-maintained?

Answer 6

Comments
Correct indentation
Variables and sub programs should be appropriately named
Global Variables used only when necessary
Overall easy to understand

Question 7

Syntax Errors:

Answer 7

Compiler or interpreter doesn’t understand code due to the code not following rules or grammar.

Question 8

Logic Errors

Answer 8

When the program can’t run due to something unexpected.

Question 9

Syntax Errors: How to find?

Answer 9

Diagnosed by Interpreter or compiler.

Question 10

Logic Error: How to find?

Answer 10

Diagnostic testing using a test plan.

Question 11

Performance test:

Answer 11

Test how quickly certain features run and their impact on computer resources

Question 12

Usability test:

Answer 12

Test how user friendly the interface and features are.

Question 13

Security Test:

Answer 13

Tests vulnerability to attacks and security of data.

Question 14

Load/Stress test:

Answer 14

How program runs under extreme conditions e.g lots of users at the same time.

Question 15

Functionality Test:

Answer 15

Tests if program meets initial requirements.

Question 16

Iterative testing:

Answer 16

Multiple Development cycles to refine and adjust code to requirements of the customer.

Question 17

Final testing

Answer 17

One development Cycle, all features of code added at once. The program is tested against initial requirements and sold.

Question 18

Normal Data

Answer 18

things a user is likely to input

Question 19

Extreme (Boundary) Data

Answer 19

Values at the limit of which the program should handle

Question 20

Errorneous Data

Answer 20

Inputs the program shouldn’t accept

Question 21

IDE: What does it stand for?

Answer 21

Integrated Development Environment

Question 22

Translators: What into what?

Answer 22

Any language into machine code.

Question 23

Compiler: What does it do?

Answer 23

All source code at once into an executable file;Only needed to use once; Returns list of errors for program after compiling is complete. Once compiled runs quickly.

Question 24

Interpreter: What does it do?

Answer 24

Translates and runs code one line at a time; Needed every time to run program; Will return the first error and then stop; Programs run more slowly.

Question 25

Low-Level languages:

Answer 25

One line of code is equal to one line of machine code; Made for one type of machine or processor; Difficult to read, understand and modify; More direct control of CPU and-so runs more memory efficiently and faster; Programmer needs to know of the internal structure of CPU.

Question 26

High-Level Languages:

Answer 26

Don’t have a lot of control of CPU; Easier to read, understand and manipulate; Can more easily store data without knowing of memory structure; Each line represents multiple lines of machine code; Will work for multiple machines and processors.

Question 27

Assemblers; What are they?

Answer 27

Assemble assembly language into machine code. Each assembler is unique to the CPU.