A2 Chapter 13. Data Representation

Question 1

What is a variable in programming?

Answer 1

• A named location in memory used to store data.
• The value of a variable can change during program execution.

Question 2

What is a constant in programming?

Answer 2

• A named location in memory with a value that cannot be changed during program execution.
• Used to store fixed values.

Question 3

What are data types in programming?

Answer 3

• Categories of data that define the operations that can be performed on the data and the way the data is stored.
• Examples: Integer, Float, String, Boolean.

Question 4

What is an array in programming?

Answer 4

• A collection of elements of the same data type, stored in contiguous memory locations.
• Accessed using an index.

Question 5

What is a function in programming?

Answer 5

• A block of code designed to perform a specific task.
• Can be reused multiple times in a program.

Question 6

What is the difference between a procedure and a function?

Answer 6

• Procedure: A block of code that performs a task but does not return a value.
• Function: A block of code that performs a task and returns a value.

Question 7

What is recursion in programming?

Answer 7

• A technique where a function calls itself to solve smaller instances of the same problem.
• Used in problems like factorial calculation, Fibonacci sequence.

Question 8

What are control structures in programming?

Answer 8

• Constructs that control the flow of execution in a program.
• Types: Sequence, Selection (if-else), Iteration (loops).

Question 9

What is a loop in programming?

Answer 9

• A control structure that repeats a block of code as long as a specified condition is true.
• Examples: For loop, While loop.

Question 10

What is the purpose of an if-else statement?

Answer 10

• A control structure used to execute different blocks of code based on a condition.
• Allows decision-making in a program.

Question 11

What is a switch/case statement?

Answer 11

• A control structure that allows a variable to be tested for equality against a list of values.
• Executes the block of code corresponding to the matching case.

Question 12

What is the difference between a for loop and a while loop?

Answer 12

• For loop: Executes a block of code a specific number of times.
• While loop: Executes a block of code as long as a condition is true.

Question 13

What is a nested loop?

Answer 13

• A loop inside another loop.
• The inner loop is executed completely for each iteration of the outer loop.

Question 14

What is an exception in programming?

Answer 14

• An error that occurs during the execution of a program.
• Can be handled using try-catch blocks to prevent program crashes.

Question 15

What is the purpose of debugging?

Answer 15

• The process of finding and fixing errors or bugs in a program.
• Ensures the program runs correctly and efficiently.

Question 16

What is object-oriented programming (OOP)?

Answer 16

• A programming paradigm based on the concept of objects.
• Objects are instances of classes, which can contain data (attributes) and methods (functions).

Question 17

What are the four main principles of OOP?

Answer 17

• Encapsulation: Hiding the internal state of an object and requiring all interaction to be performed through an object’s methods.
• Abstraction: Hiding complex implementation details and showing only the necessary features.
• Inheritance: A mechanism for creating a new class using the properties and methods of an existing class.
• Polymorphism: The ability to present the same interface for different underlying forms (data types).

Question 18

What is a class in OOP?

Answer 18

• A blueprint for creating objects.
• Defines the attributes and methods that the objects created from the class will have.

Question 19

What is an object in OOP?

Answer 19

• An instance of a class.
• Contains data (attributes) and methods (functions) to manipulate that data.

Question 20

What is the difference between compile-time and run-time errors?

Answer 20

• Compile-time errors: Errors detected by the compiler during the translation of source code to machine code.
• Run-time errors: Errors that occur during the execution of a program.

Question 21

What is a constructor in OOP?

Answer 21

• A special method used to initialize objects of a class.
• Called automatically when an object is created.

Question 22

What is inheritance in OOP?

Answer 22

• A mechanism that allows one class to inherit properties and methods from another class.
• Promotes code reuse and hierarchical class relationships.

Question 23

What is method overloading?

Answer 23

• A feature in OOP where multiple methods in the same class have the same name but different parameters.
• Allows different ways to call a method depending on the input.

Question 24

What is method overriding?

Answer 24

• A feature in OOP where a subclass provides a specific implementation of a method already defined in its superclass.
• Allows a subclass to provide a specific behavior for a method.

Question 25

What is a try-catch block?

Answer 25

• A structure used to handle exceptions in a program.
• The code in the try block is executed, and if an exception occurs, the code in the catch block is executed.

Question 26

What are the two types of data types and explain the difference?

Answer 26

1. Non-composite which can be defined without referencing another data type
2. Composite which refers to other data types in its definition

Question 27

Pseudo code syntax for an enumerated data type

Answer 27

TYPE <identifier> = (value1, value2, value3, ... )
Note
1. Type names usually begin with T to aid the programmer</identifier>

2. The values are not strings so are not enclosed in quotation