SDD

Question 1

What is the difference between a singly and a doubly linked list?

Answer 1

A singly linked list stores each piece of data with a pointer to the next item (so can only be traversed in one direction), a doubly linked list also stores the pointer to the previous item (so it can be traversed in both directions)

Question 2

What are the advantages of a linked list over an array?

Answer 2

• More dynamic (easier to add and remove items, length not fixed)
• To insert or delete items only pointers need to be changed

Question 3

What are the disadvantages of a linked list over an array?

Answer 3

• List needs to be traversed to reach a required item (can’t be indexed)
• Takes up more memory to store pointers

Question 4

What is the definition of an object?

Answer 4

An instance of a class with instance variables and methods

Question 5

What is the definition of properties and methods?

Answer 5

Class variables and procedures/functions respectively

Question 6

What is the definition of a class?

Answer 6

A template to create an object with class attributes and methods

Question 7

What is the definition of a sub-class?

Answer 7

A class that inherits its attributes and methods from its super-class

Question 8

What is the definition of encapsulation?

Answer 8

When information is hidden from some objects to allow for public and private variables

Question 9

What is the definition of inheritance?

Answer 9

When a sub-class derives its variables and methods from its super-class

Question 10

What is the definition of instantiation?

Answer 10

Creating an instance of the class

Question 11

What is the definition of polymorphism?

Answer 11

When a sub-class redefines an inherited attribute or method

Question 12

What are the steps for a binary search?

Answer 12

• Set the minimum to the first index (0) and the maximum to the last (length of array - 1)
• Start a conditional loop that runs while min <= max
• Set the middle index to (min + max) / 2
• If the item at the middle index is greater than the target then set max to mid - 1
• If the item at the middle index is smaller than the target then set min to mid + 1
• Otherwise, return the middle index (or the item at the middle index)

Question 13

What are the requirements for a binary search?

Answer 13

All data must be sorted

Question 14

What are the steps for an insertion sort?

Answer 14

• Start an unconditional loop from index 1 to the index of the last list item
• Store the value of the currently indexed item
• Store a temporary copy of the current index (so that it can be modified)
• Start a conditional loop that runs while the temporary index is greater than 0 and the item at the temporary index is greater than the current item
• Set the item at the temporary index to the item at the index before
• Subtract one from the temporary index
• Outside of the conditional loop, set the item at the temporary index to the current item

Question 15

What are the steps for a bubble sort?

Answer 15

-Declare a variable n to be the length of the array
-Declare a Boolean swapped variable to be true
-Start a conditional loop while swapped is true and n >= 0
-Set swapped to false
-Start an unconditional loop from 0 to n-2
- If the item at the current index is greater than the item at the next index then
- Set a temporary variable to the currently indexed item
- Set the currently indexed item to the value at the next index
- Set the item at the next index to the temporary variable
-Set swapped to true
-Outside of the unconditional loop, deincrement n

Question 16

What are the three sections in the boxes representing each class on a UML class diagram?

Answer 16

Class name, attributes (with - or + to represent private or public, name of attribute, and attribute type), and methods (- or +, includes constructor, getters, and setters)

Question 17

How is inheritance shown on a UML class diagram?

Answer 17

An arrow from the subclass to the superclass

Question 18

How would polymorphism be shown on a UML class diagram?

Answer 18

The method/attribute from the superclass would be included in a subclass, showing that it is being changed not just inherited

Question 19

What are the steps to insert a new node into a singly linked list?

Answer 19

A new node is created somewhere in memory, the list is traversed until the required node to be updated is found, the pointer for this node is changed, then the pointer is set for the new node (if it is at the end, pointer is set to null)

Question 20

What are the steps to delete an item in a singly linked list?

Answer 20

The memory location where the node is stored is freed up, the list is traversed to find the previous node, the pointer is updated to be the memory location of the node after the deleted item

Question 21

When are structure diagrams created?

Answer 21

As part of the top down analysis (breaking a problem down into smaller subproblems in order to make it easier to build a solution) of a software specification

Question 22

How is a process represented in a structure diagram?

Answer 22

A rectangle

Question 23

How is a loop represented in a structure diagram?

Answer 23

A box with rounded edges (or ellipse)

Question 24

How is a selection (if statement) represented in a structure diagram?

Answer 24

A hexagon

Question 25

How is a predefined function/procedure represented in a structure diagram?

Answer 25

A rectangle with double sides on the side (and single on the top and bottom)

Question 26

How is top level design used?

Answer 26

By developing a top level algorithm and then developing refinements for each module

Question 27

How is data flow shown on a structure diagram?

Answer 27

Using input and output arrows labelled with variable names to show the parameters passed in and out

Question 28

What is the purpose of a UML class diagram?

Answer 28

To give a quick overview of a system, describing its structure by showing its classes, variables, structures and types, methods of the classes, and relationships between the classes to model the static aspect of the system

Question 29

What is on a UML class diagram?

Answer 29

A box for each class, one cell in the box has the class name, a cell below has instance variables with their data type and encapsulation (e.g. -address: String is private, +bedrooms: Integer is public, -scores: Array of Score[] would be an array of objects when Score is another class), the bottom cell has methods including a constructor and getters and setters with a note of whether each is public or private (+-), inheritance between classes shown by an arrow from the subclass to the superclass, polymorphism would be shown by including a method/attribute from a superclass in a subclass

Question 30

What is the purpose of testing software?

Answer 30

Not to prove the absence of errors but to systematically eliminate the possibility of leaving errors unfound

Question 31

What is component testing?

Answer 31

Testing the individual modules of code within a program to ensure the smallest testable units function, it can take place during development

Question 32

When are stubs and drivers used?

Answer 32

To test partially completed code

Question 33

When are stubs used?

Answer 33

In top-down testing to simulate uncompleted sub-modules while testing the major module

Question 34

When are drivers used?

Answer 34

In bottom-up testing to call the sub-modules and display their output when the major module is uncompleted

Question 35

What are the steps for component testing?

Answer 35

Planning - how will it be carried out, will it use drivers/stubs, what does successful completion look like
Test data - including test cases, what inputs and what outputs from there
Execute test - follow the plan and use the test data
Record results - to compare actual output with expected output
Check for completion - if they don’t match then identify why not and repeat testing after making modifications, if they do then testing is complete