WJEC Computer Science Unit 3 Data Structures

Which of the following best describes the primary advantage of using arrays in programming?

• Arrays automatically sort data upon insertion

• Arrays allow for efficient random access to elements

• Arrays can store elements of different data types

• Arrays dynamically resize themselves without programmer intervention

Answer explanation

Arrays provide constant-time access to elements using indices, making data retrieval efficient.

In the context of data structures, what is a key characteristic that distinguishes a record from an array?

• Records can only store numeric data types

• Records store elements in a sequential manner

• Records group related data of different types under one name

• Records automatically manage memory allocation

Answer explanation

records allow grouping of related variables of different data types under a single name, facilitating organized data management.

When would it be most appropriate to use an array of records in a program?

• When you need to store a collection of unrelated data types

• When managing a list of entities with the same attributes

• When performing operations that require dynamic memory allocation

• When the number of elements is unknown at compile time

Answer explanation

An array of structures is ideal for managing multiple entities (like students, employees) that share the same set of attributes.

Consider a scenario where you need to store information about books in a library, including title, author, and ISBN. Which data structure would be most suitable?

• An array of integers

• A record containing arrays for each attribute

• An array of records, each representing a book

• A single record with a fixed number of book entries

Answer explanation

An array of structures allows each book's information to be stored as a separate structure, facilitating organized and scalable data management.

What is a potential drawback of using arrays in programming?

• Arrays can only store data of different types

• Arrays do not allow direct access to elements

• Arrays have a fixed size, which can lead to inefficient memory usage

• Arrays automatically handle memory deallocation

Answer explanation

Arrays have a fixed size determined at the time of declaration, which can lead to wasted memory if not fully utilised or insufficient space if underestimated.

Which of the following best describes the primary characteristic of a stack data structure?

• First In, First Out (FIFO)

• Last In, First Out (LIFO)

Answer explanation

A stack operates on the Last In, First Out principle, meaning the last element added is the first to be removed.

What happens when you attempt to pop an element from an empty stack?

• The operation returns null without error

• The stack automatically resizes

• An underflow error occurs

• The top element is returned

Answer explanation

Popping from an empty stack leads to an underflow error, as there are no elements to remove.

Which of the following operations is not typically associated with a stack?

• Push

• Pop

• Peek

• Enqueue

Answer explanation

Enqueue is associated with queues, not stacks.

How does the 'peek' operation function in a stack?

• Removes and returns the top element

• Returns the bottom element without removing it

• Returns the top element without removing it

• Adds a new element to the top of the stack

Answer explanation

Peek allows viewing the top element without modifying the stack.

Which of the following best describes the primary characteristic of a queue data structure?

• First In, First Out (FIFO)
  

• Last In, First Out (LIFO)

Answer explanation

A queue operates on the First In, First Out principle, meaning the first element added is the first to be removed.