9. Problem-solving and design Flashcards
What is computer system?
Made up of software, data, hardware, communications and people.
What is top-down design?
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.
What is the advantage of using top-down design?
Multiple programmers can work on the software at the same time, reducing the development time.
What is a library routine?
A set of programming instructions that is already available for use. It is pre-tested and performs regularly used operations.
What is a sub-routine?
A set of instructions that perform the actions of a subsystem (called a function in high-level language).
What is normal test data and what is the purpose of using it?
Data that should be accepted and used by the programme.
Shows that the programme does what it should with normal data.
What is erroneous/abnormal test data and what is the purpose of using it?
Data that should be rejected (e.g. negative numbers or letters when a positive number should be input.
Show that validation methods work).
What is extreme test data and what is the purpose of using it?
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.
What is boundary test data and what is the purpose of using it?
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.
What is validation?
The automated checking that data is reasonable for the process.
What is a range check?
Checks that only data within a certain range is accepted.
What is a length check and give one example?
That the length of data is an exact value or within a certain value e.g. password must be of a certain length.
What is a type check and give one example?
Checks data is of a given data type e.g. number of siblings is a positive integer.
What is a character check and give one example?
Checks the data does not include any invalid characters or symbols e.g. phone numbers have only digits and +.
What is a format check and give one example?
Checks that characters are in a pre-defined pattern e.g. school username starts with two numbers
What is a presence check and give one example?
Ensures something has been input e.g. postcode must be given for online order
What is verification?
Checks that data has been input correctly.
4 examples of verification
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
4 questions that test the efficiency of a solution
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?
