2.2.1 Programming techniques

Question 1

What are the three programming constructs? (3)

Answer 1

Sequence (1) branching (1) iteration (1)

Question 2

What is programming in sequence? (1)

Answer 2

Instructions run one after another (1)

Question 3

What is iteration? (1)

Answer 3

Repeating instructions or code until an end result is achieved (1)

Question 4

What is branching (1)

Answer 4

Choices that cause an algorithm to begin executing a different sequence of instructions (1)

Question 5

What are the key features of recursive algorithms? (4)

Answer 5

Recursive functions call themselves (1) Recursion requires memory in the stack (1) Each recursive call adds new variables to the stack (1) Recursion often expresses a problem in fewer lines of code (1)

Question 6

Compare recursion to iteration (4)

Answer 6

Recursion uses more memory than iteration (1) Recursion declares new variables each call while iteration uses the same variables (1) Recursion can run out of memory while iteration will not (1) Recursive functions call themselves while iterative ones don’t

Question 7

Compare global to local variables (4)

Answer 7

Global variables are retained in memory permanantly (1) while local variables are cleared from memory when module exits (1) Global variables can be accessed from anywhere in memory (1) while local variables can only be accessed within their module (1)

Question 8

What is the difference between byref and byval? (2)

Answer 8

byref refers to the location of the variable. Changes made change the original variable (1) byval takes a copy of the variable. Changes are made to the copy (1)

Question 9

What is a module / subprogram? (1)

Answer 9

A repeatable section of code (1)

Question 10

What is the difference between a procedure and a function? (2)

Answer 10

A function returns a value (1) a procedure does not (1)

Question 11

What are the advantages of coding using sub programs? (4)

Answer 11

Small sub programs are easier to code / modify (1) Each sub program can be called multiple times (1) Avoids repeated code (1) Can reuse in other programmers (1) Tasks can be given to other programmers to complete as sub programs (1).

Question 12

What are the advantages of coding with an IDE? (4)

Answer 12

Likely to include editor (1) compiler (1) and run time environment (1) May have autocorrect / autocomplete (1) May have debug features like breakpoints and stepping (1)

Question 13

What are the key features of objects? (4)

Answer 13

Objects have a constructor (1) attributes (variables assigned to instance) (1) methods (subroutines assigned to instance) (1) Can be encapsulated (1)

Question 14

What is the difference between public and private attributes? (4)

Answer 14

Private attributes can’t be accessed from outside of the instance (1) while public attributes can (1). Private attributes are usually accessed through a get method (1) while public attributes can be accessed directly.

Question 15

What are get and set methods in classes? (2)

Answer 15

Get methods retrieve a private attribute (1) Set methods assign or change a private attribute (1)

Question 16

What are the key features of OOP? (4)

Answer 16

OOP solves problems by means of objects that interact with each other (1) OOP uses classes as templates to construct objects (1) An object has attributes and methods associated with it (1) Objects can inherit from parent objects (1)

Question 17

What is encapsulation? (2)

Answer 17

Encapsulation is the process of keeping an object’s attributes private (1) so they can only be accessed and changed via public methods (1)

Question 18

What is polymorphism? (1)

Answer 18

Subclasses overwriting the methods of parent (or super) classes (1)

Question 19

What is inheritance? (2)

Answer 19

A class retaining the methods and attributes of its parent class (1) as well has having its own (1)