2.2.1 Programming Techniques

Question 1

Sequence

Answer 1

Execution of statements or functions one after another

Question 2

Iteration

Answer 2

Where a section of code is repeated, controlled by a Boolean expression
Can be count-controlled (for) or condition-controlled (while)

Question 3

Branching/selection

Answer 3

Where a section of code is executed based on a condition, controlled by a Boolean expression

Question 4

Local Variables

Answer 4

They are declared inside a subprogram and are only visible from that subprogram. The data is lost at the end of the subprogram and they can overwrite global variables
They are stored in RAM in the stack or the heap

Question 5

Local Variables Advantages

Answer 5

+ Less likely to be altered by other modules

+ Allows code to be reused as libraries

Question 6

Global Variables

Answer 6

Declared outside any subprograms, can be accessed from anywhere in the program.
Stored in RAM in a section called Data

Question 7

Global Variables Advantages

Answer 7

+ Can be called anywhere in the program

+ Useful if various subprograms read/write

Question 8

Subroutine

Answer 8

A section of code that performs a specific task

Question 9

Functions vs procedures

Answer 9

Functions return a value, procedures do not

Question 10

Parameter passing

Answer 10

Arguments in brackets are used to pass data to a subroutine e.g. multiply(x,y)
Can be by value or by reference

Question 11

Passing by value

Answer 11

A local copy of the value of the data is passed so the value of the original data is unchanged

Question 12

Object

Answer 12

A thing that has data (attributes) with operations that can be called on that data (methods)

Question 13

Attributes

Answer 13

A property of the object

Shape could be one, round could not

Question 14

Class

Answer 14

A blueprint for an object

Question 15

Constructor

Answer 15

A method that is used to create objects based on the class

Question 16

Encapsulation

Answer 16

Wraps the attributes and methods in the class definition, hiding details of the implementation from the user
Attributes are made private and can only be accessed through public methods

Question 17

Pseudocode to define a class

Answer 17

class Classname
private attributes
…
end class

Question 18

Pseudocode constructor method

Answer 18

public procedure new (_Name)
name = _Name
end procedure

Question 19

Pseudocode get()

Answer 19

public function getName()
return name
end function

Question 20

Instantiating an object in pseudocode

Answer 20

variable = new Classname(parameters)

Question 21

Inheritance

Answer 21

When a child inherits the properties of a parent class

Question 22

Inheritance pseudocode

Answer 22

class Child inherits Parent
inherit attributes/methods with super.

Question 23

Polymorphism

Answer 23

The ability of a programming language to process objects differently based on their class.

Question 24

Object Oriented Programming Advantages

Answer 24

Code can be reused easily via libraries
Code complexity is reduced as it is not necessary to know how methods are implemented
OOPs are easier to modify and maintain

Question 25

Parameter

Answer 25

An item of data that is inputted to a subroutine and is used as a variable within the subroutine

Question 26

Passing by reference

Answer 26

The location of data is passed into a subroutine so changes may be made to the value of the data

Question 27

Variable

Answer 27

An identifier of a memory location used to store data

Question 28

Scope

Answer 28

An area of a program for which a variable is valid

Question 29

Recursion

Answer 29

A subroutine where a section of code calls itself. There must be a base case that can be met to stop an infinite loop.

Question 30

Returning values in recursion

Answer 30

The returned value is used in the previous running of the function until they have all been completed, inputs are stored in a stack frame

Question 31

IDE

Answer 31

A software that allows you to program, debug and run code

Question 32

do until loop

Answer 32

do
….
until condition

It will run the code first and then check the condition, which is different to a while

Question 33

Argument vs parameter

Answer 33

Parameters are defined in the subroutine definition, arguments are what you pass in

Question 34

Stack overflow

Answer 34

Where the call stack in a recursive function runs out of memory

Question 35

Top-down approach

Answer 35

The problem is continually broken down into subprograms until each can be represented as an individual, self-contained blackbox which performs a certain task

Question 36

Features of IDEs

Answer 36

Stepping: run a line at a time and monitor the effect
Breakpoints: set the program to terminate at a certain line so you can observe the state
Source code editor: autocompletion, indentation, syntax highlighting etc

Question 37

Recursion advantages

Answer 37

• More natural to read
• Quicker to write/ less lines of code
• The size of the problem can be continually reduced

Question 38

Recursion disadvantages

Answer 38

• Can run out of stack space due to too many calls causing it to crash
• More difficult to trace
• Requires more memory than iterative
• Usually slower than iterative due to stack maintenance

Question 39

Substring pseudocode

Answer 39

StringName.substring(start,length)

Also use for one character of a string

Question 40

Pseudocode for the character in a string at location index

Answer 40

StringName.substring(index,1)

Question 41

Pseudocode read from file

Answer 41

myFile = openRead(“filename.txt”)
line = myFile.readLine()
myFile.close()

Question 42

Pseudocode determining the end of a file

Answer 42

myFile.endOfFile()

Question 43

Pseudocode write to file

Answer 43

myFile = openWrite(“filename.txt”)
myFile.writeLine(“text to write”)
myFile.close()