1.4.1 Data Types

Question 1

Primitive Data Types

Answer 1

“The basic data types provided by a programming language as building blocks. Most languages allow more complicated composite types to be recursively construction starting from basic types. E.g. char, integer, float, Boolean. As an extension a ‘string’ data type is constructed behind the scenes of many char data types.”

Question 2

Integer

Answer 2

“A data type used to store positive and negative whole numbers

Question 3

Real

Answer 3

“A data type used to store an approximation of a real number in a way that can support a trade-off between range and precision. A number is, in general, represented approximately to a fixed number of significant digits and scaled using an exponent.”

Question 4

Floating Point

Answer 4

“A data type used to store an approximation of a real number in a way that can support a trade-off between range and precision. A number is, in general, represented approximately to a fixed number of significant digits and scaled using an exponent.”

Question 5

Character

Answer 5

“A single alphanumeric character or symbol.”

Question 6

String

Answer 6

“A sequence of alphanumeric characters and or symbols. e.g. a word or sentence.”

Question 7

Boolean

Answer 7

“Used to store the logical conditions TRUE / FALSE. Often translated to On/Off, Yes/No etc.”

Question 8

Binary

Answer 8

“Binary describes a numbering scheme in which there are only two possible values for each digit: 0 and 1. The term in computing refers to any digital encoding system in which there are exactly two possible states. E.g. in memory, storage, processing and communications, the 0 and 1 values are sometimes called “low” and “high”, respectively.”

Question 9

Sign and Magnitude

Answer 9

“A method in computing of being able to store and represent floating point real numbers (both positive and negative) as a string of pure binary digits. Uses the concepts of two’s complements, mantissa and exponent.”

Question 10

Two’s Complement

Answer 10

“A method in computing of being able to store negative numbers as string of pure binary digits. It works by turning the MSB into a sign bit, where 0 represents a positive number and 1 represents a negative.”

Question 11

Hexadecimal

Answer 11

“A numerical system of notation which uses 16 rather than 10 as its base. The 16 Hex base digits are 0-9 and the letters A-F.”

Question 12

Denary

Answer 12

“A numerical system of notation which uses 10 as its base. The 10 Decimal base digits are 0-9.”

Question 13

Floating Point Arithmetic

Answer 13

“The mathematical process of performing simply calculations on more than one floating-point number stored in binary notation.”

Question 14

Bitwise Manipulation

Answer 14

“The act of algorithmically manipulating bits or other pieces of data shorter than a word. Programming tasks that require a bit manipulation include low-level device control, error detection and correction algorithms, data compression, encryption algorithms, and optimisation.”

Question 15

Shifts

Answer 15

“An operation that moves the bits held in a register, called the shift register, either to the left or the right. There are three different types of shift: arithmetic shift, logical shift and cyclic shift. They are distinguished by what happens to the bits that are shifted out of the register at one end and what is moved in to fill the vacant space at the other end.”

Question 16

AND

Answer 16

“A logical operator used within a program. AND works by only returning TRUE if both values being compared are TRUE.”

Question 17

OR

Answer 17

“A logical operator used within a program. OR works by returning TRUE as long as either value being compared is TRUE.”

Question 18

XOR

Answer 18

“A logical operator used within a program. XOR stands for exclusive OR. It will return TRUE if the two items being compared are different.”

Question 19

Character Sets

Answer 19

“The set of symbols that may be represented in a computer at a particular time. These symbols, called characters, can be letters, digits, spaces or punctuation marks, the set includes control characters.”

Question 20

ASCII

Answer 20

America Standard Code for Information Interchange: “A character set devised for early telecommunication systems but proved to be ideal for computer systems. ASCII codes use 7-bits giving 32 control codes and 96 displayable characters (the 8th bit is often used for error checking).”

Question 21

UNICODE

Answer 21

“Standard character set that replaces the need for all the different character sets. It incorporates characters from almost all the world’s languages. It is a 16-bit extension of ASCII.”

Question 22

Adding data to a Linked List

Answer 22

• Store the data at the location indicated by the free storage pointer
• Alter the free storage pointer to the next free storage space
• Work out where in the list the new item should be inserted
• Set the pointer for the item that will precede it to the new data item
• Update the pointer for the new data item to that previously stored in the item that preceded it

Question 23

Deleting data from a Linked List

Answer 23

IF item to remove is in first position THEN
Update starting pointer value to pointer value of item you want to delete
Update free pointers
EXIT PROCEDURE
ELSE
Update pointer value in the preceding node from the one you want to delete to the value of the pointer in item to be removed
Update free pointers
EXIT PROCEDURE
END IF

Question 24

Traversing a Linked List

Answer 24

Set the pointer to the start value
Repeat
   Go to node(pointer value)
   Output data at node
   Set the pointer to the value of the next item pointer at the pointer
Until pointer = 0

Question 25

Searching a Linked List

Answer 25

``` Set the pointer to the start value Repeat Go to node(pointer value) IF data at node is search item output value and stop Else Set the pointer to value of next item pointer at the node Endif Until pointer = 0 Output “data item not found” ```

Question 26

Traversing a Graph using the Depth-first method

Answer 26

* PUSH the first vertex onto the stack * Mark vertex as visited * Repeat * Visit next unvisited vertex to the one on top of the stack * Mark as visited * PUSH vertex onto stack * IF no vertex to visit * POP vertex off stack * END IF * Until stack is empty

Question 27

6. Traversing a Graph using the Breadth-first method

Answer 27

* PUSH the first vertex onto the stack * Mark vertex as visited * Repeat * Visit unvisited vertex's connected to first vertex * PUSH vertex’s onto queue * Until all vertex’s visited * Repeat * POP next vertex from queue * Repeat * Visit unvisited vertex’s connected * to current vertex * PUSH vertex onto queue * Until all vertex’s visited * Until queue is empty

Question 28

Inserting into a Binary Search Tree

Answer 28

* If tree is empty enter data item at root and stop. * Current node = root. * Repeat steps 4 & 5 until current node is null. * If new data item is less than value at current node go left, else go right. * Current node = node reached (null if no node). * Create new node and enter data.

Question 29

Traversing a Binary Search Tree using the Preorder method

Answer 29

* PREORDER_TRAVERSE(tree) * Visit root of tree * PREORDER_TRAVERSE(left subtree) * PREORDER_TRAVERSE(right subtree)

Question 30

Traversing a Binary Search Tree using the Inorder method

Answer 30

* INORDER_TRAVERSE(tree) * INORDER_TRAVERSE(left subtree) * Visit root of tree * INORDER_TRAVERSE(right subtree)

Question 31

Traversing a Binary Search Tree using the Postorder method

Answer 31

* POSTORDER_TRAVERSE(tree) * POSTORDER_TRAVERSE(left subtree) * POSTORDER_TRAVERSE(right subtree) * Visit root of tree

Question 32

Inserting into a Stack

Answer 32

* Check to see if stack is full. * If the stack is full report an error and stop. * Increment the stack pointer. * Insert new data item into location pointed to by the stack pointer and stop.

Question 33

Deleting data / Reading from a Stack

Answer 33

* Check to see if stack is empty. * If the stack is empty report an error and stop. * Copy data item in location pointed to by stack pointer. * Increment the stack pointer.

Question 34

Inserting into a Queue

Answer 34

* Check to see if the queue is full. * If the queue is full report and error and stop. * Insert new data item into location pointed to by the head pointer. * Increment the head pointer and stop.

Question 35

Deleting data / Reading from a Queue

Answer 35

* Check to see if queue is empty. * If the queue is empty report error and stop. * Copy data item in location pointed to by the tail pointer. * Increment tail pointer and stop.

Question 36

Searching a Hash Table

Answer 36

* Feed in key to Hash function * Go directly to array index (HashValue) * IF (value = value searching for) THEN * Value found * ELSE * Follow linked list in sequence until * value found * END IF

Question 37

Inserting into a Hash Table

Answer 37

* Feed in key to Hash function * Go directly to array index (HashValue) * IF (location is empty) THEN * Insert Value * ELSE * Follow linked list in sequence until * free space found * Insert Value * END IF

Question 38

Deleting data from a Hash Table

Answer 38

* Feed in key to Hash function * Go directly to array index (HashValue) * IF (value = value searching for) THEN * Mark as empty * ELSE * Follow linked list in sequence until * value found * Mark as empty * Update free pointers in linked list * END IF