53. AQA GCSE (8525) SLR9 – 3.2 Data structures & arrays

What is a data structure?

• A tool for debugging code

• A method for writing algorithms

• A type of programming language

• A specialized format for organizing and storing data

Answer explanation

A data structure is a specialized format for organizing and storing data, making it the correct choice among the options provided.

Which of the following is NOT a basic data structure?

• Functions

• Tables

• Lists

• Arrays

Answer explanation

Functions are not considered a basic data structure as they are used to define reusable blocks of code rather than storing and organizing data.

What is an array?

• A type of function in Python

• A variable that can contain more than one data item

• A method for organizing files

• A single data item

Answer explanation

An array is a variable that can contain more than one data item, making it the correct choice among the options provided.

How are arrays indexed?

• Alphabetically

• Starting at 0

• Randomly

• Starting at 1

Answer explanation

Arrays are indexed starting at 0, meaning the first element in an array is accessed using index 0. This is the standard indexing method in most programming languages.

What is the difference between lists and arrays in Python?

• There is no difference

• Arrays are contiguous, while lists are not

• Lists can only store integers

• Lists are contiguous, while arrays are not

Answer explanation

Arrays are contiguous, while lists are not. Arrays store elements in adjacent memory locations, while lists do not have this requirement.

What does it mean when an array is described as 'static'?

• It moves around in memory

• It can change size

• It cannot change size once set up

• It can only store static data types

Answer explanation

An array described as 'static' cannot change size once set up, meaning its size remains fixed throughout its lifetime.

How can you access 'Austria' from an array of countries?

• Using index 2

• Using index 'Austria'

• Using index 1

• Using index 0

Answer explanation

To access 'Austria' from an array of countries, you need to use index 1 as arrays are zero-indexed, not 'Austria' or any other index.

What is a two-dimensional array visualized as?

• A sphere

• A table

• A cube

• A line

Answer explanation

A two-dimensional array is visualized as a table because it consists of rows and columns, similar to a table structure.

How many sets of indexes are needed to access an item in a two-dimensional array?

• Four

• Three

• Two

• One

Answer explanation

To access an item in a two-dimensional array, two sets of indexes are needed - one for the row and one for the column. Therefore, the correct answer is Two.

What is true about the data items in an array?

• They are always in alphabetical order

• They can be of different data types

• They must be of the same data type

• Only strings and integers are allowed

Answer explanation

The correct choice is that data items in an array must be of the same data type.