2.2.1 FINAL Programming techniques

Question 1

What is a data type?

Answer 1

A classification of data into groups

Question 2

What is an integer?

Answer 2

Used to represent whole numbers, either positive or negative

Question 3

What is a real?

Answer 3

Used to represent numbers with a fractional part, either positive or negative

Question 4

What is chr?

Answer 4

Used to represent a single character such as a letter, digit or symbol

Question 5

What is a string?

Answer 5

Used to represent a sequence of characters

Question 6

What is boolean?

Answer 6

Used to represent true or false values

Question 7

What is casting?

Answer 7

When you convert one data type to another data type

Question 8

What is a programming construct?

Answer 8

Determines the order in which lines of code are executed

Question 9

State the 3 types of programming constructs

Answer 9

Sequence, Branching, Iteration

Question 10

What is a sequence?

Answer 10

• Refers to lines of code which are run one line at a time
• The lines of code are run in the order that they are written from the first line of code to the last line of code

Question 11

What is a selection?

Answer 11

• The flow of the program is interrupted and a condition is tested
• Outcome of the condition will then determine which lines/block of code is run next. Two ways to write selection statements:
• IF statement: test conditions sequentially
  SWITCH statement: test an expression against multiple possible constant values

Question 12

What is an iteration?

Answer 12

• Repeating a line or block of code using a loop. It can be:
• Count controlled: When the code is repeated a fixed number of times (for loop)
• Condition controlled: When the code is repeated until a condition is met (while loop)

Question 13

What is a SWITCH/CASE statement?

Answer 13

• Type of conditional statement that provides an alternative way to perform multiple comparisons based on the value of an expression
• Useful when you have a single expression that you want to compare against multiple possible values

Question 14

What is a for loop?

Answer 14

Count controlled loop that will repeat a fixed number of times

Question 15

What is a while loop?

Answer 15

Condition controlled loop that will repeat until a condition is met
- Provides a flexible way to handle situations where the number of iterations in unknown in advance

Question 16

What is modularity?

Answer 16

Where problems are broken down into more manageable pieces
- Each piece of the problem should be carried out by one single subroutine

Question 17

What are subroutines?

Answer 17

• Standalone blocks of code and when called, they will complete a task
• The promote code reusability, modularity and organisation, enabling a programmer to write efficient and maintainable programs

Question 18

What is a function?

Answer 18

Block of code that takes in 0, 1 or more parameters, performs a set task and return a value

Question 19

What is a procedure?

Answer 19

Block of code that takes in 0, 1 or more parameters and performs a set task

Question 20

What is a parameter?

Answer 20

Pieces of data which are passed into the function or procedure to allow it to complete a task

Question 21

What are the two ways of passing a parameter?

Answer 21

• Passing by value
• Passing by reference

Question 22

What does it mean by parameter passing by value?

Answer 22

• A copy of the actual value is made and assigned to the function’s parameter
• Any changes to the parameter within the function’s scope do not affect the original value outside the function
• Function works w/ and changes its own local copy of the value
• Suitable when you want original data to be protected from being modified within the function
• When function ends, copy of the value is destroyed
• Can lead to performance overhead when working with large data structures since a copy is made

Question 23

What does it mean by parameter passing by reference?

Answer 23

• Function receives the memory address of the value rather than a copy of the value
• Any changes made to the parameter within the function directly affect the original value outside the function
• Both the function and the calling code share the same memory location
• Efficient for working w/ large data structures
• Can lead to unexpected side effects if not handled carefully, as changes made within the function affect other parts of the program

Question 24

What is recursion?

Answer 24

When a function calls itself to solve a problem or execute a task
- Uses idea of self-reference to break down complicated problems into more manageable subproblems

Question 25

What 3 features does a recursive algorithm have?

Answer 25

- Contains a stopping condition (base case) - For any input value other than the stopping condition, the subroutine should call itself (recursion) - Stopping base: Must be reachable after a finite number of times

Question 26

How does recursion work?

Answer 26

- Function must call itself with a modified input parameter until it reaches a base case - Each recursive call breaks down the problem into more minor instances until it reaches the base case

Question 27

Why is it important to have a proper stopping condition or base case when using recursion?

Answer 27

- To avoid stack overflow errors which result in program crashes - If it doesn't have a stopping condition, it will continue to call itself indefinitely, which can use up excessive memory + cause the program to malfunction

Question 28

What are the benefits of recursion?

Answer 28

- Concise: Can often be expressed in a more concise way, especially for structures e.g. trees or fractals - Simple: Simply stating what needs to be done without having to focus on the how it can make it more readable and maintainable

Question 29

What are the limitations of recursion?

Answer 29

- Inefficient use of memory: if the subroutine calls itself too many times, there's a danger of stack overflow, causing the program to crash - Debugging: recursive code can be more difficult to track the state of the program - Limited application: not all problems are suited to recursive solutions

Question 30

What are the benefits of iteration?

Answer 30

- Performance: more efficient than recursion, less memory usage - Debugging: easier to understand and debug - Wider application: more suitable to a wide range of problems

Question 31

What are the limitations of iteration?

Answer 31

- Complexity: can get very complex and use more lines of code than recursive alternatives - Less concise: compared to recursive alternatives, making them harder to understand

Question 32

What is a local variable?

Answer 32

- Declared inside a subroutine - Only accessible by that subroutine - Created when that subroutine is called - Destroyed when the subroutine ends

Question 33

What is a global variable?

Answer 33

- Declared at the top of a program, outside of any subroutine - Accessible throughout the program - Created when the program starts - Destroyed when the program ends

Question 34

What are the benefits of local variables?

Answer 34

- Encapsulate data within a particular subroutine, providing data hiding + preventing unintended access from other parts of the program - Can use the same in different functions without causing conflicts, as each local variable is confined to its own scope (easier for programmers to work w/ each other) - Have a limited lifetime + their memory is automatically reclaimed when the code block ends, making them memory efficient

Question 35

What are the drawbacks of local variables?

Answer 35

- Repeatedly creating + destroying local variables within a loop/recursive function can incur unnecessary memory overhead - Excessive use of them in deeply nested blocks can lead to code cluster + reduce code readability - Slow execution as memory is allocated dynamically when needed

Question 36

What are the benefits of global variables?

Answer 36

- Only needs to be declared once - Don't need to keep passing parameters between different modules

Question 37

What are the drawbacks of global variables?

Answer 37

- Always stored in memory while the program is running which can use up memory - Makes the program difficult to maintain as it's hard to understand where variables are changed in the program - Makes it difficult to test a single block as the programmer will need to run the entire program to set up the global variables

Question 38

What is an IDE?

Answer 38

- Software tool that provides programmers with a comprehensive + integrated platform to write, edit, compile and debug + manage their code efficiently - Designed to streamline the software development process by offering features/tools that can help programmers

Question 39

Features of IDEs that can be used to write programming code

Answer 39

- Syntax highlighting - Autocompletion (code completion) - Code comments - Auto indent

Question 40

Features of IDEs that can be used to debug programming code

Answer 40

- Variable watch window - Breakpoints - Stepping mode

Question 41

What is a class in OOP?

Answer 41

- A template for creating objects with specific attributes and methods - Way of organising code in a modular way

Question 42

What is an object?

Answer 42

An instance of a class that encapsulates attributes and methods into a single entity

Question 42

What is an attribute?

Answer 42

A data member/variable associated with a class or object, representing the state/characteristics of that class/object

Question 43

What is a method?

Answer 43

A subroutine defined within a class that encapsulates a set of actions/behaviours that can be performed by objects of that class

Question 44

What is instantiation?

Answer 44

Creating an object from a class

Question 45

What is a public method?

Answer 45

- Property of a method which allows it to be accessible from everywhere - Changes to them may impact on other parts of the codebase so should be documented whenever possible - Used when you want to provide access to certain functionalities/behaviours of an object/class to other parts of your program

Question 46

What is a private method?

Answer 46

- Property of a method which allows it to only be accessed within the same class - Changes to it have a localised impact as they can only be used internally within the class, providing more flexibility to modify them without affecting other parts of the program - Used when you have internal implementation details that should not be accessed by external code. Meant to be used only within the class itself for managing the code internally

Question 47

What is inheritance?

Answer 47

Allows a class to inherit the methods and attributes of another class

Question 48

What does inheritance promote?

Answer 48

Code reuse - Allows derived classes to inherit and utilise the existing code from the base class - Promotes better organisation and maintainability

Question 49

What two entities does inheritance involve?

Answer 49

- Base class and the derived class - Derived class inherits the characteristics of the base class, meaning it can access and use the methods/attributes defined in the base class

Question 50

What is encapsulation?

Answer 50

Data held within a class can only be accessed through its methods

Question 51

Benefits of encapsulation?

Answer 51

- Ensures data remains secure and not misused by controlling access to them using access modifiers (e.g. public, private) - Organises code by keeping related data and methods together within an object Promotes code reusability (the same object/class can be used in diff. part of a program without rewriting the code

Question 52

What is polymorphism?

Answer 52

- Allows objects to take on different forms/behaviours - Different objects can share the same name/behaviour but can work in different ways

Question 53

What are the benefits of polymorphism?

Answer 53

- Makes code more flexible, reusable and easier to maintain - Allows flexibility and reusability in programming, making it easier to write and manage code - Objects can be treated as belonging to a common group, even if in different classes, making code more versatile and adaptable to changes