1 - Fundamentals of programming

Question 1

What is SELECTION and nested selection? Give an example of both.

Answer 1

Selection - the process of choosing what action to take based on certain criteria, EG If, else and case

Nested selection - the process of placing one set of instructions with another, EG Else If

Question 2

What is ITERATION? Name the different types and give examples.

Answer 2

Iteration - repeating the same thing again and again
Definite –> repeats set number of times
EG For loop
Indefinite –> repeats until condition is met
EG Do While
Nested –> for within a for

Question 3

Define variable/ constant declaration

Answer 3

Process of defining variables and constants in terms of a name and a data type

Question 4

Define assignment

Answer 4

Process of giving a value to a variable or constant

Question 5

Define a subroutine

Answer 5

A named block of code carrying out a specific task saving the rewriting of the same code over and over

Question 6

Why is it important to have meaningful identifier names?

Answer 6

• Easier to debug (find and correct errors)
• Easier to update code when further versions of code are created
• Easier to understand if several programmers working on it at once

Question 7

Advantages of constants:

3

Answer 7

• If you want to change a value, you only have to change it in the constant declaration
• Reduces likelihood of errors
• Easier to read and understand (Of named constants_

Question 8

Define constants :

Answer 8

An item of data who’s value doesn’t change

Question 9

Define variables

Answer 9

Short term memory used to store temporary values

Question 10

How do you do exponentiation in c#?

Answer 10

Math.Pow(3,2)

–> 3^2 = 9

Question 11

Difference between rounding and truncating:

Answer 11

Rounding decreases the number of digits while maintaining a value approximately equivalent.
Truncating (Match.Truncate) cuts of numbers after a certain dp.

Question 12

Define exception handling:

Answer 12

Process of dealing with events causing the current subroutine to stop (errors). EG division by 0, so use try and catch

Question 13

Name the 3 types of errors and explain:

Answer 13

Syntax error –> forgot closing bracket or misspelling
Run - time error –> Works fine but breaks when run
Logic error –> program runs but gives incorrect answer

Question 14

Define local variables:

Answer 14

Only accessible within the subroutine and exist only while the subroutine is executing.

Question 15

Define global variables:

Answer 15

Accessible from all parts of program

Defined at top in c#

Question 16

Why locals more desirable than global?

Answer 16

+ Once subroutine run, removed from memory (FREE UP MEMORY).Whereas global stay in the memory while the program is running
+ Can use same local name in different subroutines but treated as separate
+ Can’t accidentally change local value stored somewhere else in program
- Use global when want to declare variable needed to be accessible by all parts of code

Question 17

Recursion:

Answer 17

Defining a subroutine within itself
+ Produce smaller, more natural solutions to a problem
- Take up a large amount of resources storing return addresses and states

Question 18

Stack frames:

Answer 18

A collection of data about a subroutine
It stores:
- Return address - point it should go back to once down with call
- Parameters - data passed into a subroutine
- Local variables - variables in current subroutines that it should restore

Question 19

Debug

Answer 19

Process of finding and correcting errors in a program

Question 20

Define a subroutine

Answer 20

A named block of code designed to carry out a specific task which saves the rewriting of lots of the same code again and again

Question 21

Uses of subroutines

Answer 21

Allow for:
Reuse of code
Structure your programming
Easily incorporate other people’s code

Question 22

Subroutines by ref

Answer 22

Directly changing the value and anything happening to it within procedure will change the original value

Question 23

What does a parameter do?

Answer 23

Allows to pass values to procedures an fucntions that you declare.

Question 24

What are arguments?

Answer 24

The piece of data given to a function when called

Question 25

Advantages of subroutines

Answer 25

• Easier to test and debug as each subroutine is self contained
• Very large projects can be developed by more than 1 programmer
• Can use top-down approach to develop whole project

Question 26

What is procedural orientated programming?

Answer 26

Languages where the programmer specifies the steps needed to carry out to achieve a result
The adding of procedures so a program, especially long, is easier to work with

Question 27

Advantages of procedural orientated programming

Answer 27

• Reuse code without retyping it, reducing time it takes to write
• Less chance of bugs that would come about from rewriting
• Clearer of what program does and how, as name of procedure explains what lines of code are for
• Reduces length of program making it easier and faster to read and debug
• Allow compilers to make more optimizations as compilers detect re-used code and use this to take shortcuts

Question 28

What is a hierarchy chart?

Answer 28

A diagram demonstrating the design of a system from the top down
- Starting from the program name, programmer breaks problem down into a series of steps. Each step then broken down into a series of steps

Question 29

Example of a hierarchy chart

Answer 29

• Programs are made up of modules
• Modules made up of subroutines
• Subroutines made up of algorithms
• Algorithms made up of lines of code
• Lines of code made up of statements (instructions) and data

Question 30

Define Imperative programming

Answer 30

Languages based on giving computer commands and procedures to follow

Question 31

Define OOP

Answer 31

Uses objects to make code easier to read and work with

Question 32

What is a class?

Answer 32

Defines methods and property/attribute fields that capture the common behaviours and characteristics of objects
IE defines the properties and methods of a group of similar objects
EG car - colour - manufacturer etc

Question 33

What is an object?

Answer 33

A specific instance of a class
All have the same methods and properties from same class
Created by using a constructor, implicit or explicit and a reference to the object assigned to a reference variable of a class EG Nissan, blue

Question 34

What is instantiation?

Answer 34

Process of creating an object from a class
IE creating an actual instance of an object using the properties and methods described in the class

Question 35

What is encapsulation?

Answer 35

Concept of putting properties, methods and data in one object

Question 36

What is inheritance?

Answer 36

Concept that properties and methods in one class (base class) can be shared with a subclass

Question 37

What is aggregation?

Answer 37

Creating new objects creating existing ones based on how they are related 
EG Care may have passengers, they come and go
Repped by whit diamond line in class diagram

Question 38

What is composition aggregation?

Answer 38

Creating an object containing other objects that will cease to exist if the containing object (base class) is destroyed 
EG Every car has an engine 
Repped as black diamond in class diagram

Question 39

What is association aggregation?

Answer 39

Where an object is made up of 1 or more objects but isn’t entirely dependent on those objects for its own existence

Question 40

What is polymorphism?

Answer 40

Ability of different types of data to be manipulated with the same method

• Classes inherit methods from base class but data in these new classes are different types
• Instead of defining new methods, polymorphism enables original method to be redefined so that it will work with new data

Question 41

What is overriding?

Answer 41

Where a method described in subclass takes precedence over a method with the same name in the base class

Question 42

Advantages of OOP

Answer 42

• Easy to amend programs as only effected method needs changing (as program written in modules)
• Easy to add new functionality to a program by adding a new module
• Groups of programmers can work independently on self-contained modules
• Objects can inherit attributes and behaviors, making code reusable throughout program
• Changes to code will not accidentally affect results of another routine

Question 43

What is a method?

Answer 43

The code or routines contained within a class

Question 44

What are the behaviours of methods?

Answer 44

STATIC - method can be used w/o an object of the class being instantiated 
VIRTUAL - method defined in the base class that can be overridden by method in subclass where it will be used (polymorphism) 
ABSTRACT - method not supplied in base class (hence provided in subclass). Object used as interface between method and data

Question 45

Name the design principles when using OOP

Answer 45

-Encapsulation that varies
Everything that varies should be out into its own class, hence methods and properties subdivided into as many classes needed to reflect real-life scenario
-Favour composition over inheritance
Use aggregation/ composition to combine existing objects to make new ones - less error prone and simpler maintenance
-Program to interfaces, not implementation
Programs written as interfaces (defines methods being used) rather than individual implementation of class