2.2.1 Programming Techniques

Question 1

What are the 3 conditions for Recursion

Answer 1

1. Contains a stopping condition
2. For any input value other than the stopping condition, the subroutine should call itself
3. The stopping condition should be reachable within a finite number of time.

Question 2

Compare iteration and recursion, which is more memory efficient?

Answer 2

Iteration.

Question 3

Advantages of recursion

Answer 3

For certain problems, they can be represented in fewer lines of code — less prone to error

Question 4

Disadvantages of recursion

Answer 4

1. Inefficient use of memory
   In recursive approach, every time a recursive function calls itself, the processor needs to remember where it was before it jumps to the new copy.
   The processor also needs to remember that values of all the previous variables using stacks, which takes up space in memory.
2. Difficult to trace
3. Stack overflow – call stack runs out of memory

Question 5

Define Sequence

Answer 5

A programming constructs that code is executed line by line.

Question 6

Define branching/selection

Answer 6

A certain block of code is run if a specific condition (write the exact condition in the question) is met.
Using IF statement

Question 7

Define iteration

Answer 7

A block of code is executed a certain number of times or while a condition is met

Question 8

Two types of iteration with examples

Answer 8

Count controlled : for
Condition controlled : while, repeat until

Question 9

Define recursion

Answer 9

A programming construct in which a subroutine calls itself during its execution, until a certain condition is met.

Question 10

State and explain some features of an IDE

Answer 10

• Auto complete : predict the word that gonna be typed in to avoid spelling mistakes
• Syntax highlighting : run one line at a time to check result
• Stepping : can identify features (reserved word) quickly
• Breakpoint : stop the code at set point to check variables, helping debug

Question 11

Define class

Answer 11

A template for an object and defines the state and behaviour of an object

Question 12

What are the two things define the objects’ properties and the action of the object

Answer 12

Attributes and Methods

Question 13

Define Instantiation

Answer 13

Use a class to create an object

Question 14

Define an object

Answer 14

An particular instance of a class

Question 15

Define Encapsulation

Answer 15

A technique used to implement the principle of information hiding

Attributes are declared as private and can only be altered by public methods