Software Design & Development: Unit 2 - Data Types and Structures

Question 1

What is a 1-D array?

Answer 1

A data structure containing a set of variables of the same data type, with positions stored as an integer index.

Question 2

What is a 2-D array?

Answer 2

An array of 1-D arrays

Question 3

What is a record structure?

Answer 3

A data structure containing a set of variables of different data types (similar to a database record, made of different field types)

Question 4

What is an array of records?

Answer 4

An array containing a set of records

Question 5

What is a linked list?

Answer 5

A set of items organised sequentially just like an array, but each item includes a link to the next item in the list

Question 6

What are advantages of using a linked list? (2)

Answer 6

• Dynamic data structure, which means that its size is not fixed
• Memory efficient, only needs to be as large as the number of items to be stored, instead of as large as the total possible number of items stored

Question 7

What is a disadvantage of using a linked list?

Answer 7

Not possible to identify a specific item directly using its index - as in an array - and to identify an item you have to walk through the list from beginning to end.

Question 8

What is a stack?

Answer 8

A data structure acting like a vertical list, where data elements can be added or deleted only from the ‘top’ of the stack (Last In First Out)

Question 9

What is an advantage of using a stack?

Answer 9

It is useful where a situation calls for the most recent item to be accessed

Question 10

What is a queue? (2)

Answer 10

• A data structure where data items are inserted and retrieved at different ends
• In a queue two pointers are used, one to point to the head of the queue and one for the end (First In First Out)

Question 11

What is an advantage of using a queue?

Answer 11

It is useful where a situation calls for events to be placed in a queueing system waiting to be processed in order.

Question 12

Implement a 2-D array

Answer 12

DECLARE example AS ARRAY OF ARRAY OF INTEGER INITIALLY []
SET example TO [ [] ] * X #array with X elements, each an empty array

FOR column FROM 0 TO Y DO #Y=max column no.
FOR row FROM 0 TO Z DO #Z=max row no.
SEND example[column][row] TO DISPLAY
END FOR
END FOR

Question 13

Implement an array of records

Answer 13

RECORD record IS{STRING name, INTEGER number}

DECLARE example AS ARRAY OF record INITIALLY []

SET example[0] TO { name=”A’ , number=1 }
SET example[1] TO { name=”B” , number=2 }
SET example[2] TO { name=”C” , number=3 }