Chapter 16 Data Representation

Question 1

What is a user-defined data type?

Answer 1

A user-defined data type is a data type that derived from an existing data type

Question 2

Name both of the user-defined data types

Answer 2

1. Non-composite user defined data types

2. Composite user-defined data types

Question 3

Name the two non-composite user-defined data types

Answer 3

1. Enumerated

2. Pointer

Question 4

Name the two composite user-defined data types

Answer 4

1. Record

2. Set

Question 5

Define ‘enumerated data type’

Answer 5

A list of possible data values

Question 6

Define ‘pointer data type’

Answer 6

A pointer data type is used to reference a memory location

Question 7

Define ‘record data type’

Answer 7

A data type that contains a fixed number of components, which can be of different types

Question 8

Define ‘set data type’

Answer 8

A set data type allows a program to create sets and to apply the mathematical operations defined in set theory

Question 9

What are the operations in set theory?

Answer 9

1. Union
2. Difference
3. Intersection
4. Include an element from the set
5. Exclude an element from the set
6. Check whether an element is in a set

Question 10

Define ‘Objects and classes’

Answer 10

An object is an instance of a class; the class specifies how instances are created and how they behave

Question 11

What is the advantage of a user-defined data type to an in-built one?

Answer 11

User-defined data types are less error-prone and makes a program easier to understand

Question 12

What is the advantage of using a record data type?

Answer 12

It allows the programmer to collect together values with different data types when these form a coherent
whole

Question 13

What are the two defined file types?

Answer 13

1. Text file

2. Binary file

Question 14

What is a text file?

Answer 14

A text file stores data in the form of alphabets, digits and other special symbols by storing their ASCII values

Question 15

What is a binary file?

Answer 15

A file designed for storing data to be used by a computer program, it stores as a sequence or a collection of bytes

Question 16

What is a serial file?

Answer 16

A serial file contains records which have no defined order. A typical use of a serial file would
be for a bank to record transactions involving customer accounts

Question 17

What is a sequential file?

Answer 17

A sequential file has records that are ordered, it is typically used to store data for long periods of time

Question 18

What is a direct-access file?

Answer 18

Direct-access files are sometimes referred to as ‘random-access’ files, in them, the position of a record is calculated using an algorithm

Question 19

What is a real number?

Answer 19

A real number is one with a fractional part

Question 20

What is floating point representation?

Answer 20

A representation of real numbers that stores a value for the mantissa and a value for the exponent

Question 21

What is fixed point representation?

Answer 21

Fixed point representation is when an overall number of bits is chosen with a defined number of bits for the whole number part and the remainder for the fractional part

Question 22

What is a mantissa?

Answer 22

A fixed-point real number in two’s complement form and an understood position for the binary point

Question 23

What is the exponent?

Answer 23

A signed integer in two’s complement representation