Programming Theories

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Stephen Rosister (S0511437) Unit -6 and 15

Programming Theories

In this written document I will explain the key features, advantages and disadvantages of

Object Orientated, Event Driven and Procedural programming types.

Task 1

Object Orientated

This type of programming is based around objects instead of procedures. The objects, also

known as data structures, are grouped instructions and data. OO was designed because

there were difficulties in creating complex systems using a procedural approach.

OO also offers a less number of functions compared to low level programming (procedural)

which interacts directly with the pc’s hardware, but because OO and procedural are

programming techniques therefore it can be used at multiple levels.

Inheritance – Inheritance makes the code re-usable because the OO code is split in to

classes, for example, the code for ‘animal’ would be one class with all the data that every

animal has; this is the parent class. The individual animal classes such as ‘dog,’ ‘cat’ and

‘horse’ would inherit the code for animal, meaning the OO developer doesn’t need to re-

write the code for animal over and over again. Each individual animal class is classes as a

child. The child classes inherit everything from the parent class. Because the code is

inherited by the child class the code doesn’t need to be re-written.

Polymorphism – When polymorphism is used in OOP the developer has the ability to

create a variable, function or object that has the ability to change its form to suit of

programs. Polymorphism is nothing but a function with the same name exhibiting two ormore characteristics. For example;

DrawShape()

Drawshape(intRadius) = Circle

DrawShape(intLength, intBreadth) = Rectangle



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This code is an example of overloading, there is also another type of polymorphism called

overriding; method overriding enables programmers to allow a derived class to alter the

behaviours it inherited from its base class.

For example,

Public Overrides Function GetRating() As Integer

creditrating = Clnt(Balence) \ 100

If creditrating > 5 Then

creditrating = 5

End If

Return creditrating

End Function

Encapsulation

In OOP, Encapsulation is a language mechanism for restricting access to some of the

‘objects’ components. The data that has been encapsulated cannot be accessed unless the

specific means are used. When programming there are three different levels of access:

Public, Protected and Private, each one will only allow for certain codes to access them

depending on their access level. Public level access, allows all classes to access the data

without any restrictions. Protected data is restricted to functions of inheritance classes; for

example is the first class has the code needed to access the data all the classes that inherit

that class also gain access to the data. Private data can only be accessed by the classes that

have the ‘access codes’ to that data. Private is the highest level of protection.

Objects that are encapsulated do not need to reveal all their attributes and behaviours. It

should only reveal the interfaces that are needed to interact with it.

Advantages

Due to inheritance and polymorphism OO is re-usable. The code is very easy to maintain due

to inheritance (see above) and it is also re-useable due to the inheritance of class from

parent to child classes.

Disadvantages



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I of the main disadvantages of OOP is that it is very complex and difficult to pick up for new

programmers. OOP is a high level concept therefore it takes more time to execute because

many other codes run in the background at the same time. There is an increased burden

on the part of an OO developer because of the complexity and detail needed in OO code.

Event Driven

A program that responds to user input, this is determined by an event (event trigger), sensor

outputs or user inputs, such as mouse clicks, timers, key presses or messages from other

programs or threads.

Advantages

Event driven programming allows for a more interactive programs, almost all modern GUI

programs use event driven programming, for instance the desktop of any operating system,

for example Windows xp, windows 7 and the Macintosh operating systems all are event

driven. The icons on the desktop must be clicked on before anything will happen. The use

of Event Driven programming allows sensors and other hardware to interact with the

software more easily. Event Driven programming can also be implemented using hardware

interrupts so the computer will use less power. Event Driven programs integrate well with

GUI and other UI’s; it is also easy to set it up to receive messages from other threads.

Disadvantages

For simple Event Driven programming is often more complex and would be harder to use

than other types of programming. The flow diagrams of Event Driven are usually less logical

and obvious. Programs made using Event Driven Programming are memory intensive. Theclasses made when using this type of programming are not re-usable or are hard to

implement in to other applications, it is also complex to master and is often not portable to

other operating systems. Event Driven is generally only useful in GUI programming and

games where you chose what happens.



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After clicking the start icon, an event driven code runs and opens the start menu.

Procedural

This type of programming, unlike Object Orientated Programming, uses procedures instead

of objects. Each code must run in a certain order and cannot be re-arranged. The next

stage of the code cannot start until the previous has finished. The procedures can also be

knows as, routines, sub-routines, methods or functions. The functions should not be

confused with mathematical functions but are similar to those used in functional

programming. The procedures simply contain a series of steps that will be carried out. Any

of the procedures may be called at any point during a programs execution, by another

procedure or itself. Procedural programming is the most consistent of all programming

languages.

Advantages

Procedural programing will run faster than Object Orientated Programming, the procedures

also allow for quicker completion. This type of programming is easier to pick up for people

who are new to programming

Disadvantages

Although it is faster than OOP it isn’t as flexible as other types of programming. For very

large programs the codes get very long and if a mistake is made the programmer will have

to go through the code and find each part that is wrong and change it.



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Task 2

When choosing a programming language a number of different factors should be taken in

to consideration; for example, the operating system that is currently in use, if the program isgoing to be web based, is the program going to be used on a desktop or a hand held device,

how much will it cost to train staff so they can use the language that will be chosen and the

ease and cost of maintaining the finished product.

Operating System

If a developer chose a programming language that was compatible with apple and the

company or corporation that came to them for a program were using windows 7 or a Linux

operating system the overall product wouldn’t work and the program would have to be re-

made at the programmer’s expense. For example military applications will be written in

languages such as ADA whereas windows programming is well supported by languages such

as Visual Basic™. The Java programming language is best suited for use in internet programs

and mobile device applications such as smart phone apps and games. The Visual Basic

programming language is only compatible with PC hardware that is running off a Windows™

operating system.

Platform (Desktop, Handheld device, Web Based)

The platform on which a program is going to be made is very important because a mobile

devise will need less programming than a conventional desktop PC. The mobile applications

tend to be limited to single player game mode (no online gaming capability) which means

there would be no need for the code to run online gaming. Therefore without the code for

online gaming the code would be shorter than games that do need the code for online

gaming. If an application is being used on the internet the program would need to support

many users at once because many people in the modern world have access to the internet,

if an online program only had the code to support up to a few user at a time it would crash a

lot because many people would want to use the site or program at the same time.

Cost to train staff



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If the staff at a programming company could all use Visual Basic, there would be no point in

paying for them all to learn C#. The only reason for the staff to learn C# would be if the

client wanted game programming. Also if the program was for use on mobile devices,

desktops and the internet the program would have to be made in Java. When choosing a

programming language the cost of training and the eventual outcome of the completed

program. When training staff the company are losing money because the staff are not

programming and they also have to pay for a tutor to come in and teach the staff whatever

language is being used. The choice to use a language that is not first choice would be

decided on the total cost of training staff and the final bill for the client when the program

gets completed.

Ease and cost of maintenance

When a program has been finished the chances are there will be bugs (mistakes) in the

coding; for example when Infinity Ward™ release a new game such as Call of Duty© there

will be bugs within the game that let the gamer do things that aren’t meant to happen. The

bugs can be anything from getting out of the map to not getting hit in a game of zombies.

When the bugs are found the games company need to be able to fix them; the harder it is to

find, alter the code and release an update for the new code to take effect will cost the

company money. If the code is easy to maintain the company will not have to spend too

much time finding and fixing the bugs. For example if the game is made using OOP the bug

will most probably be found and fixed relatively quickly due to the inheritance of the code.

Once the first mistake has been found the changed code will be inherited by the classes and

all the bugs get fixed.

Task 3

Selection

Selection statements allow a choice to be made as to which a set of statements are carried

out next.

Private Sub btnGo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)

Handles btnGo.Click

Dim input As String input = txtInput.Text



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Dim input As String

input = txtInput.Text

If input = "A" Or input = "B" Then

MessageBox.Show("well done you typed in and " & input)Else

MessageBox.Show("Why is it so hard to type an A or a B?")End If

When I enter a letter it to the text box the sequence runs and gives me a message box

with a small message inside it. The message box will not appear until text is entered

in to the text box.

Private Sub btnGo2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)

Handles btnGo2.ClickDim input As Integer

input = CType(txtInput2.Text, Integer)

If input > 10 And input < 20 Then

MessageBox.Show("Well done")

Else

MessageBox.Show("Not so good")

End If

When a number lower than ten is entered in to the second text box a message box will

appear saying ‘Not so good’ and if a number between 10 and 20 is entered the message box



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will appear saying ‘Well done.’ The two message boxes say something different depending

on what is entered in them because of the ‘If’ coding.

Iteration

Iteration is a loop; there are three different types of loop coding. In ‘for’ loops you know

how many times the code will loop, whereas ‘while/until’ loops will loop any number of

time and you do not know how many times it will loop. ‘Do’ loops will loop at least once but

you do not know how many times after the first loop it will loop again.

Dim check As Boolean = True

While (check)

lstNumbers.Items.Add("looped again")End While

Randomize()

Dim n As Integer = Rnd() * 10

Do

If n <> 8 Then

lstNumbers.Items.Add(n.ToString())

Else

check = False

End If

n = Rnd() * 10Loop While (check = True)

A ‘While’ or ‘Do’ loop will loop until a condition is met. The user doesn’t know how many

loops will take place.

Sequence

Procedural programming is a sequence. Programs that are set in to sequences will onlyhappen in one order and it will not skip any of the programming steps.

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)

Handles MyBase.Load

cbbNames.Items.Add("Ross")

cbbNames.Items.Add("Stephen H")

cbbNames.Items.Add("Nico")cbbNames.Items.Add("Matt O")

cbbNames.Items.Add("Liam")

cbbNames.Items.Add("Kieran")

cbbNames.Items.Add("Matthew R")

cbbNames.Items.Add("Stephen R")cbbNames.Items.Add("Ivan")



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cbbNames.Items.Add("Dan")

cbbNames.Items.Add("Yueharo")

With cbbNames.Items

.Add("Joe B")

.Add("Daniel")

.Add("Jack").Add("Joe")

.Add("Luke")

End With

When a program needs to execute certain procedures such as calculations, accepting user

input and outputting data; the program instructions are followed in sequence.

For example when the coding above is executed the names are listed in the order that they

have been entered.

Task 4

Data type Data size Example data Data range

String (variable-

length)

10 bytes + (2*string

length)

1+1=11 0 to approximately 2

billion Unicodecharacters.

Integer 4 Bytes Whole numbers

between the data

range eg. 956,254

-2147483648 to

+2147483647

Double (Double-

prescience floating-

point

8 Bytes Up to 14 significant

digits

Decimal 12 Bytes Large positive and

negative numbers

with 28 significantdigits

Date 8 Bytes Date and Time A Date and Time

Variable

Char (single

Character)

2 Bytes A Unicode value. (A

code that represents

characters on the

keyboard)

0 to 65535

(unsigned)

Byte 1 Byte Whole Numbers 0 to 255Boolean 1 Byte Values that can only True or False



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be True of False

Every variable has a data type. This sets the type of data that will be stored and the range of

values that a variable can accept. The data type will also define how the data will be

formatted when displayed. Choosing the correct data type for your variables is crucial.

Inappropriate types could result in excessive amounts of storage set aside when it is not

needed. If a variable cannot accommodate the size of the value assigned to it, the system

will crash.

Data that is needed to do calculations must be placed in a numeric data type such as an

integer, or single. However if you insert non-numeric data the program will crash. Code can

be used to stop a user from entering non-numeric data in to s text box that will only work

with numeric data; for example,

Dim n As Integer

'converts the key that has been pressed

'in to an ascii value n = AscW(e.KeyChar)

'checks to see if the key pressed

'is not a number If (n < 48 Or n > 57) And n <> 8 And n <> 46 Then

'if it is not a number then

'tells the program that the key press has been dealt with e.Handled = True

ElseIf n = 46 And txtItemPrice.Text.IndexOf( ".") <> -1 Then

e.Handled = True

'only allows one decimal place to be entered Else

If (txtItemPrice.Text.Length > txtItemPrice.Text.IndexOf(".") + 2) And

txtItemPrice.Text.IndexOf(".") <> -1 And n <> 8 Then

e.Handled = True

'only allows two digits after the decimal place

End If

End If

For instance the code above is for a change calculator user input box, the code stops the

user from entering letters and other non-numeric data but it does allow the input of a

decimal place, this is allowed by;ElseIf n = 46 And txtItemPrice.Text.IndexOf(".") <> -1 Then

e.Handled = True 'only allows one decimal place to be entered



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Bibliography

http://msdn.microsoft.com/en-us/library/47zceaw7(VS.80).aspx

http://en.wikipedia.org/wiki/Object-oriented_programming

http://en.wikipedia.org/wiki/Procedural_programming

http://en.wikipedia.org/wiki/Event-driven_programming

http://wiki.answers.com/Q/What_are_the_advantages_of_event_driven_programming

http://www.answers.com/topic/procedural-language

http://wiki.answers.com/Q/What_is_an_inheritence&altQ=Inheritence_in_oop&isLookUp=

1

http://wiki.answers.com/Q/What_is_polymorphism_in_oops

http://wiki.answers.com/Q/What_are_advantages_and_disadvantages_of_OOP_'Object_Or

iented_Programming'&altQ=Disadvantage_of_OOP&isLookUp=1

http://en.wikipedia.org/wiki/Polymorphism_in_object-oriented_programming

Edexcel Information Technology Level 3 Book 1. BTEC National – Karen Anderson, Alan

Jarvis, Allen Kaye, Jenny Lawson, Richard McGill, Jenny Phillips, Andrew Smith – Pages 166

and 173

Visual Basic .NET – A complete Object-Orientated Programming Course Including Unified

Modelling Language (UML) – Phil Jones with a foreword by Tim Sneath of Microsoft – Pages

216, 385, 439







http://wiki.answers.com/Q/What_is_an_inheritence&altQ=Inheritence_in_oop&isLookUp=1



http://wiki.answers.com/Q/What_are_advantages_and_disadvantages_of_OOP_'Object_Oriented_Programming'&altQ=Disadvantage_of_OOP&isLookUp=1















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