9. Problem-solving and design

Question 1

What is computer system?

Answer 1

Made up of software, data, hardware, communications and people.

Question 2

What is top-down design?

Answer 2

The breaking down of a computer system into a set of sub-systems, then breaking each sub-system down into a set of smaller sub-systems until each sub-system performs just a single action.

Question 3

What is the advantage of using top-down design?

Answer 3

Multiple programmers can work on the software at the same time, reducing the development time.

Question 4

What is a library routine?

Answer 4

A set of programming instructions that is already available for use. It is pre-tested and performs regularly used operations.

Question 5

What is a sub-routine?

Answer 5

A set of instructions that perform the actions of a subsystem (called a function in high-level language).

Question 6

What is normal test data and what is the purpose of using it?

Answer 6

Data that should be accepted and used by the programme.

Shows that the programme does what it should with normal data.

Question 7

What is erroneous/abnormal test data and what is the purpose of using it?

Answer 7

Data that should be rejected (e.g. negative numbers or letters when a positive number should be input.
Show that validation methods work).

Question 8

What is extreme test data and what is the purpose of using it?

Answer 8

Numbers at the limits of what should be accepted (e.g. 0 and 100 for a percentage).
Shows the validation limits have been set up properly.

Question 9

What is boundary test data and what is the purpose of using it?

Answer 9

Numbers on the boundary of what should be allowed (e.g. -1 and 0 for a percentage).
Shows the validation limits have been set up properly.

Question 10

What is validation?

Answer 10

The automated checking that data is reasonable for the process.

Question 11

What is a range check?

Answer 11

Checks that only data within a certain range is accepted.

Question 12

What is a length check and give one example?

Answer 12

That the length of data is an exact value or within a certain value e.g. password must be of a certain length.

Question 13

What is a type check and give one example?

Answer 13

Checks data is of a given data type e.g. number of siblings is a positive integer.

Question 14

What is a character check and give one example?

Answer 14

Checks the data does not include any invalid characters or symbols e.g. phone numbers have only digits and +.

Question 15

What is a format check and give one example?

Answer 15

Checks that characters are in a pre-defined pattern e.g. school username starts with two numbers

Question 16

What is a presence check and give one example?

Answer 16

Ensures something has been input e.g. postcode must be given for online order

Question 17

What is verification?

Answer 17

Checks that data has been input correctly.

Question 18

4 examples of verification

Answer 18

Double entry (data is entered twice)
Screen/visual check (user is shown what they just input and asked to check it is right)
Parity check
Checksum

Question 19

4 questions that test the efficiency of a solution

Answer 19

Does the solution work for all data sets?
Does the solution have unnecessary processes that are never used?
Are any action repeated more than necessary?
Can the solution be simplified and still work?