Software Development

1
Software Development

• Higher

2
Software

• What is software?
• All programs that allow hardware to do something
  useful and interesting
• You probably use several different pieces of
  software every day/week
• Examples?
• What is hardware?
• Everything that you can touch

3
Software

• A piece of software is simply a list of
  instructions that are fed to the computer and
  executed
• It is therefore important that these instructions
  are in the correct order and the instructions
  themselves are correct

4
Questions(Int2)

• What is the meaning of the term hardware?
• Give three examples of software.
• Complete the following table

5
The Development Process

• The software development cycle is a systematic
  approach to producing software. The software
  development life cycle can be summed up in the
  following stages
• Analysis
• Design
• Implementation
• Testing
• Documentation
• Evaluation
• Maintenance

6
Development Process

• It can be difficult to remember all of these
  stages in order.
• This little mnemonic might help.
• Or, you might develop your own.
• A Dance In The Dark Every Monday

ocumentat ion
valuation
aintenance
nalysis
mplementation
esting
esign
7
Software Development Process

• Analysis To look at the problem and determine
  what the solution might be. Use existing systems
  or write a new program? Turn the rough idea into
  an exact description. What are the inputs and
  outputs? What type of computer will it be run on?
  All of these questions must be answered at this
  stage.

8
Who does it?

• The systems analyst is the person who is
  responsible for the analysis stage

9
Skills of the Systems Analyst

• Usually a skilled and experienced programmer
• Good people skills
• Good communication skills

10
What do they do?

• Interview clients
• Observation notes of existing practice
• Questionnaires
• All of these are categorised as requirements
  elicitation

11
The Importance of Being Anal

• The systems analyst has to be very detailed and
  accurate
• So the rest of the process runs smoothly
• Examples of what could go wrong?
• After requirements elicitation the analyst will
  create a requirements specification
  (program/problem specification) contains a
  full problem description, inputs and outputs etc

12
Put the following in the correct order

• 1. Create a user manual
• 2. Get the team together to discuss what the
  games purpose is and what kind of things the
  player will be able to do
• 3. Create the game
• 4. Fix the problems found in testing. Produce
  downloadable updates for the game
• 5. Design the games characters and worlds.
  Produce a plan for when certain parts of the game
  should be finished
• 6. Make sure the game works properly
• 7. Allow some people to play the game and ask
  them what they think of it

13
Blob Diagram(analysis)

• Used to determine the inputs and outputs to a
  program, using tea example

sugar
Tea bag
Used tea bag
Making tea
water
Boiled water
milk
Cup of tea
14
Blob Diagram

• Create a blob diagram for the following program
• A program that asks the user the length and
  breadth of a floor in metres. It will also ask
  the user the price of the carpet they will use
  (in m2) and then tells the user how much carpet
  will be required and the total cost
• When you have done this, try to create the
  program in Visual Basic

15
Blog Entry The Software Development Lifecycle

• Higher
• The 7 stages of the SD Lifecycle
• Analysis What happens here, who does it, how do
  they do it and what do they produce
• Techniques what techniques are used

• Int2
• The 7 stages of the SD Lifecycle
• Analysis What happens at this stage and what is
  produced
• Blob diagramy

16
Blog Entry The Software Development Lifecycle

• Update your blog on the Software Development
  lifecycle to include all of the new things you
  have learned about each stage.

17
Software Development Process

• Design jumping straight into coding a program
  is not a good idea. This stage is important as
  the details of the program are worked out here.
  Things like how the screen will look, how the
  user will interact with the program and how the
  program might be structured. There are a variety
  of design methods. Pseudocode and structure
  diagrams are two of the most common.

18
Pseudocode

• Like an English version of the program but can
  have code in it too if the designer knows how
  they will code it
• If done properly the pseudocode should match the
  program line for line
• Take making a cup of tea as an example
• 1. Fill kettle
• 2. Boil kettle
• 3. When kettle boiled pour hot water in cup
• 4. Add tea bag, milk and sugar
• 5.Stir
• We can then use this as the design for our program

19
Your turn

• Write the Pseudocode for the following
• A program that asks the user which times table
  they wish to be displayed. The program will then
  display that times table in a list box

20
Structure Diagram

• Fairly simple, take the tea making example

Making tea
Fill kettle
Boil kettle
Stir
When kettle boiled pour into cup
Add milk, sugar
21
Structure Diagram(with data flow)
Length breadth
Length breadth
area
area

• Indicates what variables are passed in and out of
  procedures

22
Structure diagram

• Draw the following structure diagrams(with data
  flow)
• A program that calculates the area of peoples
  gardens when given the length and breadth in
  metres
• A program that works out the average test score
  for a pupil from 3 different test scores

23
Software Development Process

• Implementation This is the process of turning
  the design into a suitable programming language.
  We will use a High Level Language, called Visual
  Basic.
• Testing A great deal of time is spent on
  testing. A wide range of conditions will be
  tested. Normal, extreme and exceptional testing.

24
Documentation

• User Guide Details of how to use the program
• Technical Guide The minimum specifications
  required of the computer you wish to install the
  software on. Will also contain installation
  instructions

25
Maintenance

• The 7th and last stage of the development process
• Continuous
• 3 types of maintenance
• Corrective
• Perfective
• Adaptive

26
Maintenance

• Corrective
• Fix bugs that appear when program is in use
• Company might make downloadable patch available
• Perfective
• Adding new features
• Might mean a new a version of the software is
  created
• Adaptive
• When software needs to take account of some
  change in the conditions it operates in
• E.g. new version of operating system for example
  was designed for Windows XP and adapted to run on
  Windows Vista

27
Order these steps correctly

• A writing a user guide and technical guide for
  the software
• B Deciding the game you want to create, and
  what features you want it to have
• C adapting the game to run on a different type
  of computer
• D Actually writing the program code
• E Checking that the program does what it is
  supposed to do, is easy to use, and can be fixed
  if there is a problem
• F working out the details of what the screens
  will look like, what menus and functions there
  will be, and other detailed aspects of the
  program
• G Getting users to try out the program to make
  sure it works under most conditions

28
ANALYSIS the user requirements are determined
at this stage
DESIGN Software and Program design are detailed
at this stage
MAINTENANCE-upgrading
SOFTWARE DEVELOPMENT LIFECYCLE
EVALUATION - refinements
IMPLEMENTATION actual program put into operation
DOCUMENTATION technical and user guide drawn up.
TESTING errors and bugs corrected
29
High Level Languages (HLLs)

• Just like human language, there are many
  different types of programming language
• Each has been designed to solve a specific type
  of problem
• Each has its own strengths and weaknesses

30
High Level Languages (HLLs)

• Visual Basic is an example of a High Level
  Language
• High Level Languages contain normal words and
  are close to English
• This makes them relatively easy for us to
  understand
• However, as we know computers only understand
  binary

31
Low Level Languages

• Low level languages are closer to the language
  that the computer can understand
• It is very difficult to track down and fix bugs
  using these languages

32
Machine Code

• Computers only understand binary, the only input
  a processor will accept is a binary code and it
  will only give this as output, these are known as
  Machine Codes
• There are a number of problems with Machine Codes
• They are different from processor to processor
• Hard for humans to understand and use
• Difficult to find and fix errors

33
Questions

• Which type of language (high or low) is easier to
  understand?
• Which type would be easier to correct if it had a
  mistake in it?
• Name 2 low level languages
• Name 2 high level languages
• Explain the main differences between high and low
  level languages
• List 2 advantages of high level languages

34
High/Low Level Languages

• High
• Visual Basic
• Pascal
• Logo
• Java

• Low
• Machine Code
• Assembler

35
How does a computer understand a HLL?

• The short answer is it doesnt
• What could we do if we wanted to communicate with
  a Chinese person who doesnt speak English and we
  dont speak Chinese?
• Get a translator
• This is exactly what a computer does
• Every HLL has a translator to translate it to
  code the computer understands

36
Translators

• There are 2 different types of translator
• Compiler and Interpreter
• Each has strengths and weaknesses

37
Interpreters

• Take each line one at a time and convert to
  machine code
• This is the reason that Visual Basic tells you
  when youve made a mistake at the end of each
  line
• This means when a program is run the line has to
  first be translated and then executed, which
  slows the program down

38
Interpreters

• The program needs to be translated each time it
  is run so there is no way to speed the process
  up.
• This means the interpreter and the program must
  be stored after the program is complete
• Where the program goes the interpreter is needed

39
Compiler

• Translates the program when it has been completed
• It takes the whole program and converts it to
  machine code at once
• This machine code can be kept and run as many
  times as you want
• Means the program runs faster
• Only the compiled program needs to be stored

40
Questions

• Name the two main types of translator programs
• Which one translates the whole program into
  machine code before it is executed?
• Which translates the program line by line?
• Why do machine code programs run more quickly on
  a computer than high level language programs?

41
Text Editors

• Implementation of a program takes place in a high
  level language(HLL)
• High level languages are very close to English
  and therefore we can use tools much like those we
  would use when typing an essay e.g. cut and paste
• HLLs can be typed in a word processing package
  and saved as a text file, ready for translation
  to machine code

42
Scripting Language and Macros

• This unit is mostly concerned with the process of
  developing stand alone applications in high level
  languages
• However small programs can be developed within
  some existing application packages
• These are called macros
• Macros are time saving programs written in a
  scripting language which can be activated by a
  series of key strokes for repeated use. They will
  only work with an application program, they
  cannot exist alone.
• They can extend the functionality of an
  application
• They customise applications

43
Questions

• What is a macro?
• What type of language is used to write macros?
• What are the advantages of using macros?
• Describe 2 examples where a macro could be useful.

44
Variables(Implementation)

• We declare variables in our program to hold
  values that might change throughout the execution
  of our program
• We will be mainly using 3 variable types in this
  course. String (for text), Integer (whole
  numbers) and Single (numbers with fractions)
• If we declare a variable as a certain type the
  program will expect this type to be used when
  trying to set a value for a variable

45
Variables(Implementation)

• It is good practice to declare all of the
  variables at the start of the program
• Dim name as String
• Dim age as Integer
• Dim rate_of_pay as Single
• Dim is short for Dimension

A space in memory
name
age
rate_of_pay
46
Which variable type?

• 0.456
• Jones
• -56
• 291
• Mike
• 17.886
• 3.14
• R2D2

47
Which variable type?

• 0.456 Single
• Jones String
• -56 Integer
• 291 Integer
• Mike String
• 17.886 Single
• 3.14 Single
• R2D2 String

48
Exercise

• Which of the following excerpts of code will give
  errors?
• (a) Dim name as String
• Name Derek
• Dim price as Single
• price Derek
• Dim price as Integer
• price 30

49
Formatting Output

• It is good practice to format your output
  accordingly e.g. if you are outputting a monetary
  value it should look like this 3.90
• There is a function in VB6 that takes care of
  this for you, cleverly it is called the Format
  function and can be used like this
• Format(price, currency) this has the effect of
  formatting the variable price so that when it is
  output to the screen it will have a sign added
  automatically

50
Formatting Output

• Some other examples
• Format(price, .0) to one decimal place
• Format(price, .000) to 3 decimal places
• Format(average, percent) ??
• Format(time, .00\s)??

51
Naming Conventions

• Label start with lbl
• TextBox start with txt
• Command Button cmd
• Picture box pic
• List Box - lst

52
Variable Names

• Remember that variable names give us an easy way
  to refer to a storage location in memory
• Rather than using the address
• Variables will be used in every program
• In large programs there can be hundreds of
  variables
• Good variable names make a program more readable

53
Variable Names

• It is therefore very important and good practice
  to use sensible, meaningful variable names.
  Sometimes this means using multiple words
• Some no nos
• Whitespace is not allowed
• E.g user age
• Use capitals to de-limit multiple words
• userAge
• roomWidth
• Or use under score
• User_age
• Room_width
• Choose one method and stick to it!

54
Commenting

• It is good practice to comment your code so that
• You can understand the program
• You can see where you left off if you dont get a
  program finished
• Makes it readable
• Helps maintenance as often in software companies
  more than one person will work on a program so
  comments help others see what you are trying to
  do more easily.

55
Commenting

• To comment we simply type an apostrophe () after
  the line of code and anything after it will be
  ignored by the computer e.g.
• Dim name as String declares a name variable
  with the type string

56
Making Decisions

• Often the programs we write wont always go
  straight from start to finish
• In some programs we will want to make decisions
  and based on these decisions the program might
  execute an alternative set of instructions e.g.
• If condition then
• Action 1
• Action 2
• Else
• Alternative Action 1
• End If

57
IF statements

• The technique we use to make decisions is an IF
  statement
• IF (userNumber 1) Then
• lblOutput.Caption You win the car!
• Else
• lblOutput.Caption You Win nothing!
• End If

58
More Complex IF Statements

• Sometimes a decision is not as straightforward as
  simply IF something True then do something
• We might need to look at more than one thing
  being true or a combination of true and false
• We have a set of operators that can be used for
  this

59
Complex IFs

• For example OAPs to qualify as an OAP, men need
  to be 65 or over and women need to be 60 or over
• This couldnt be represented with a normal IF
  statement
• If (sex m) AND (age gt 65) then
• Print you are an OAP
• Else
• If (sex f) AND (age gt 60) then
• Print You are an OAP
• Else
• Print you are not an OAP, YET!
• End If
• End If

60
Multiple IFs

• It is possible that your program will need to
  make more than one decision and we can use
  multiple Ifs to do this e.g
• If mark gt 70 then grade A
• If mark gt 60 then grade B
• If mark gt 50 then grade C
• Else
• Grade Fail

61
Multiple IFs

• In the example on the previous slide, even if the
  mark is greater than 70 the other 2 IF statement
  lines of code will be executed
• This means the program is executing 2 lines of
  code unnecessarily
• This is inefficient use of resources(processor
  time/main memory)

62
An efficient alternative

• A more efficient way to code this would be a CASE
  statement
• Select CASE mark
• Case Is gt70
• Grade A
• Case Is gt 60
• Grade B
• Case Is gt 50
• Grade C
• End Select
• Select CASE is more efficient because if mark is
  75 the grade will be set to A and the remaining
  Case Is lines are ignored, therefore not
  executing unnecessary code

63
InputBoxes

• So far we have used text boxes to get the user
  input. We are now going to use a special code
  word in Visual Basic, InputBox
• When an InputBox is used your program will open a
  new window with a prompt for the user to enter
  something

64
InputBoxes

• InputBoxes are used in the following way
• Variable_name InputBox (Prompt to the user,
  Title of InputBox)
• Or a real example
• UserName InputBox(Enter your name, Enter
  Name)

65
InputBoxes

• This code
• UserName InputBox(Enter your name, Enter
  Name)
• Would produce the following window when the
  program is run

66
MessageBoxes

• InputBoxes are a nice way to collect input to
  your program as a lot of the work is done for
  you.
• There is a similar special word we can use for
  output, MsgBox
• Used like this
• MsgBox (Thanks for using my program)

67
MessageBoxes

• This code MsgBox (Thanks for using my
  program)
• Produces the following

68
Fixed Loops

• So far, every program you have written starts at
  the beginning and executes each line till it
  reaches the end and then stops
• To repeat a program you need to run it again
• It is often useful to be able to repeat a number
  of lines of a program

69
Fixed Loops

• If we know how many times we want to repeat
  something we can use a fixed loop
• For counter 1 to 10
• Form.Print Mr McAlpine is the best!
• Next
• Will print the statement to the form 10 times

70
Loops using a variable

• If we want a loop that can be repeated a variable
  number of times we can get the user to input the
  value for the loop to stop
• For counter 1 to user_input
• Print this is an example of a variable loop
• Next

71
ForNext other ways to control the loop length

• We can control the loop length using a command
  called Step
• For counter 1 to 20 Step 2
• This would have the effect of adding 2 to the
  counter each time round the loop rather than the
  default 1
• We can put whatever number we like after the
  step, depending on how we want the loop to
  operate
• For counter 10 to 1 Step -1
• Would have the effect of going down from 10 to 1

72
Questions

• Write the Visual BASIC coding of a For..Next loop
  to produce each of the following lists of numbers
• 3,6,9,12,15,18..33,36
• 0,9,18,27..99
• 10,9,8,7,6,5,4,3,2,1,0
• 0,0.75,1.5,2.25,3,3.75,4.5
• 50,40,30,20,10,0,-10,-20,-30,-40,-50
• 1,4,9,16,25,36,49,64(hint these are all numbers
  squared)

73
More Loops

• So far the loops we have used have gone for a set
  or fixed number of times depending on us setting
  it up or the user saying how long they want the
  loop to be
• There is another kind of loop that can be used
  when we are unsure of when we want a loop to end
• Conditional Loop

74
Do..Loop Until

• One type of VB6 loop we can use when we are
  unsure of the number of times a loop will be
  repeated is called a Do..Loop Until, it looks
  like this
• Do
• Lines of code to be repeated
• Loop Until condition

75
Do..Loop Until

• Here is a real example of this kind of loop
• Do
• userInput InputBox (What is 22?)
• Loop Until userInput 4
• This will keep asking the user the question until
  they enter 4(the correct answer)

76
WhileWend Loop

• A While loop is also a conditional loop
• While ( user_password ltgt p4w0rd)
• user_passwordInputBox(Enter password)
• Wend
• This loop will continue whilst the users entry is
  NOT p4w0rd

77
What kind of Loop?

• Program needs to take in a list of ten names
• Program needs to keep going until the user enters
  the word end
• Program continues until user enters a 4 digit pin
• Program needs to take in four different pieces of
  information from the user

78
Input Validation

• There is a saying in computing which goes
• Garbage In, Garbage Out (GIGO)

79
(No Transcript)
80
Input Validation

• It is common for the companies who do things like
  this to blame it on computer error
• More often these type of errors occur because the
  program has been fed invalid data

Wrong data in
Wrong data out
Program
81
Input Validation

• If we design our program properly we should be
  able to prevent or at least restrict the amount
  of wrong data our user is allowed to enter
• An example we have designed a program that
  allows teachers to enter their students
  percentages and it calculates a grade

82
Input Validation

• So the teacher is entering the percentages. They
  want to enter 59 but are in a hurry and enter
  559.
• This would most likely give the student an A
  when they shouldve in fact got a B
• Garbage In, Garbage Out!
• This could be prevented by making it impossible
  to enter a score of more than 100

83
Input Validation

• A score of over 100 could be described as Invalid
  in this sense
• Invalid data, is data which makes no sense
• To prevent invalid data being entered we can
  include our code for data input in a conditional
  loop that will only stop when valid data is
  entered

84
Invalid Data

• A program asks a user to enter a date in
  day/month/year format. Give an example of an
  entry that would be considered invalid and also a
  valid entry
• A program asks a user to enter a 5 digit number,
  give an example of an invalid entry and a valid
  entry.

85
Input Validation

• Note that Input Validation does not stop mistakes
  from occurring it simply stops invalid data being
  entered.
• For example it would stop a percentage of 105
  being entered but if someone entered 59 instead
  of 49, validation does not pick up on this
• The process of catching erroneous data is called
  verification, which is outside the scope of this
  course

86
Input Validation

• The process of input validation always follows a
  standard pattern
• Standard patterns save programmers time when
  programming
• A pattern like this is called a standard algorithm

87
Input Validation

• Here is a simple version of the standard
  algorithm for input validation
• Do
• Prompt user for valid input
• If input is invalid, warn user
• Loop until data is valid

88
Other Standard Algorithms

• Input Validation is an example of a Standard
  Algorithm
• There are 4 others that you need to know about
• Finding a minimum/maximum, Counting Occurrences
  and Linear Search

89
Standard Algorithms

• The pattern for Input validation is the same in
  all scenarios
• This saves programmers time when designing
  programs
• There are many other instances of these patterns
  that are re-useable
• They are called STANDARD ALGORITHMS

90
Finding Minimum/Maximum

• These algorithms search lists of numbers and
  return the value of the minimum/maximum
• E.g in the following list
• 14, 67, 24, 2, 69, 9, 100, 101
• Minimum?
• Maximum?

91
Finding Min

• Will usually be used in conjunction with an array
• Set min first element in array
• For length of array
• If current array element lt min then
• Min current array element
• Next
• Print min

92
Finding Max

• Will usually be used in conjunction with an array
• Set max first element in array
• For length of array
• If current array element gt max then
• Max current array element
• Next
• Print min

93
Counting Occurrences

• Works its way through a list of numbers, as it
  does, it counts the amount of times a certain
  value appears
• E.g. how many times does 3 appear here?
• 4, 7, 3, 8, 6, 3, 9, 0, 3, 5

94
Counting Occurrences

• Usually involves using an array
• To_find Dave
• For length of array
• If current array element to_find
• Counter counter 1
• Next
• Print Counter

95
Linear Search

• Searches through a list looking for a particular
  item and returns where in the list the item
  appears
• e.g. search for blue
• Red, green, yellow, orange, blue, pink
• 5 would be returned as blue is the 5th item in
  the list

96
Linear Search

• Usually used along with an array
• Name InputBox Enter a name to be found
• For counter 0 to length of array
• If namearray(counter) Name
• Display Name found at counter
• End If
• Next

97
Which standard algorithm would we use to solve
these problems?

• Search through a list of names to find at what
  place the name Steve appears
• Make sure the user enters a number between 1 and
  10
• Find the month in a list with the lowest rainfall
• Counting the number of times Rangers have won the
  league from a list of league winners

98
Questions

• Which standard algorithm would be used by the
  national census to
• Find out how many people called Mary live in the
  UK
• Find out the oldest person living in the UK
• Discover whether or not there was an individual
  living in the UK call Stan D. Ard-al-Gorithm

99
Pre-Defined Functions

• These carry out standard operations that are
  commonly used
• They exist for strings (text) and numbers
  (Integers)

100
Pre-defined String Functions

• UCase (string) capitalises the string
• LCase (STRING) puts string to lower case
• Len (string) returns the length of the string
• Mid(string, start point, lengthrequired) returns
  a section of the string starting at the character
  specified by the start point and the length
  specified by the lengthrequired

101
SubStrings

• Essentially taking a chunk out of a string to use
  for something else like generating a password or
  to look for a pattern in a string
• Using
• Mid(string to be used, start position, number of
  letters in the substring)

102
Concatenation

• Sometimes we will want to output multiple values
  using a single line of code e.g
• MsgBox(Your total bill is totalCost)
• Or
• MsgBox(Customer Name name VbCrlf
  Customer Address address)
• Using the sign is called Concatenation
• It can be used as many times as necessary to get
  your output looking like you want it

103
Concatentation

• Remember though that there is a Format function
  so
• Something like
• MsgBox(Format(price, Currency))
• Will have the same effect as
• MsgBox ( price)

104
Questions

• Match these descriptions to the pre-defined
  function
• Description Pre-defined function
• Returns the ASCII code of character Mid
• Selects a group of characters out of a
  string Asc
• Turns any character into upper case LCase
• Takes an ASCII code and returns the character
  it UCase
• represents
• Changes any character to lower case Len
• Counts the number of characters in a
  string Chr

105
Questions Continued

• If sentence What is 25 times 8?), what would
  be the output from
• A) Mid(sentence,1,1)
• B) Mid(sentence,1,4)
• C) Mid(sentence,9,2)
• D) Mid(sentence,19,1)

106
Pre-Defined Numeric Functions

• INT(variable containing a fraction) would remove
  the fractional part, leaving the whole number
• ROUND(variable to be rounded) rounds the number
  to the NEAREST whole number
• SQR(variable) gives the square root of any number

107
User Defined Functions

• We can create functions of our own e.g
• Function calc_area(length as single, breadth as
  single) as single
• Dim area as single
• Area length breadth
• Calc_area Area
• End Function
• We can then use the function as follows
• Private sub cmd_click()
• Dim length as single
• Dim breadth as single
• Dim area as single
• Area calc_area(length, breadth)

108
Arrays

• Arrays are useful for times when we need to store
  lists of related data
• For example 6 test marks for a pupil, we would
  normally do this
• Dim mark1 as integer
• Dim mark2 as integer
• Dim mark3 as integer
• Dim mark4 as integer
• Dim mark5 as integer
• Dim mark6 as integer

109
Arrays

• This would give us 6 independent variables in
  memory

110
Arrays

• However if we just use this command
• Dim mark(5) as integer
• We define an array where each variable is
  referred to by an index e.g. 0,1,2,3

111
Arrays

• An array is very useful as the program can refer
  to the whole array at once or any single element
• Arrays would normally be used in conjunction with
  a loop

112
Testing

• Any product created will go through rigorous
  testing
• A wide range of conditions will be used e.g. not
  only expected inputs in the case of a program
• These will be planned at the design stage
• Testing will be systematic and comprehensive
• Systematic means the testing is planned and not
  just random tests
• Comprehensive means every aspect is tested

Testing can only prove the presence of bugs, not
their absence. Testing finds bugs, de-bugging
removes those bugs
113
Normal Testing

• Make sure the program does what it should when
  being used normally
• A program expects a number to be entered between
  0 AND 40
• Normal testing would test that the program did
  what it should for numbers 1-39

114
Extreme/Boundary testing

• Making sure the program can handle values at the
  extreme or boundary of what is considered normal.
• Using our 0 to 40 program
• Extreme tests would be -1, 0, 40, 41

115
Exceptional testing

• Making sure the program can handle situations or
  inputs that are unexpected or that the program is
  not designed for
• Using our 0-40 program
• Things like 3000000, y , n , -45690, hello

116
What kind of testing

• A) program looking for a persons age and the
  test data used is hello, 1000000, steve,
  oioi70780
• B) program looking for a 4 digit pin code and the
  data used is 0000, 0001, 9999
• C) program looking for the price of a slab 0.50,
  1.23, 2.45, 5.60

117
Testing and Robustness

• Testing all conditions provides useful evidence
  about he robustness of the software
• Robustness is the ability of the program to cope
  with erroneous/unexpected data

118
Testing

• Testing is carried out by Independent Test teams
• Other programmers from within the organisation
• Or perhaps contractors
• Or potential clients
• Or combination of all of the above
• Testing is carried out at various stages

119
Acceptance Testing

• Acceptance testing is sometimes called Beta
  testing
• Carried out on the premises where the software
  will be used, by the people who will use it
• Given unrestricted access
• Allowed to enter unpredictable input to test the
  behaviour of the program

120
Exhaustive Testing

• Testing functionality with all possible valid and
  invalid data
• Is this possible?
• So how much is enough?
• How important is the project?

121
Documentation

• After testing has been completed we move onto
  stage 5 of the development process
  Documentation
• Any product you buy, software or hardware will
  come with a User Guide to tell you how to use the
  product
• This may also contain a tutorial taking you
  through the use of the product step by step
• Becoming more prevalent to use an electronic
  format
• More eco-friendly but can also be updated with
  the software

122
Documentation

• As well as the user guide for the software, there
  will also be a Technical Guide of some sort
• Usually this is of no interest to most users, but
  will contain information about the specification
  of computer required
• E.g. RAM, how fast a processor and which
  Operating System the computer needs
• Will also contain instructions on installation of
  the software
• Might also contain information on trouble shooting

123
Evaluation

• Stage 6 and the final stage before the product is
  distributed
• Involves reviewing the software to see if it is
  of the quality required
• We will look at three headings
• Fitness for Purpose
• User Interface
• Readability

124
Evaluation

• User Interface
• Is program easy to use?
• Is it clear what each menu, command and button is
  for?
• Could it be improved in any way?

125
Evaluation

• Fitness for Purpose
• Does software do as it should under all
  reasonable conditions?
• Check against the program specification to make
  sure (analysis stage)
• Look at test results and making sure the program
  is free of bugs

126
Evaluation

• Readability
• No direct concern of the user
• Important for other programs to understand how
  the program works
• Is it possible for another programmer to read and
  understand the code
• Needs to be if there will be updates performed at
  a later date

127
Evaluation(Higher)

• The following questions will be asked
• Is the program robust?
• Is the program reliable?
• Is the program reliable?
• Is the program portable?
• Is the program efficient?
• Is the program maintainable?
• These are expanded in the notes

128
Evaluation

• What 3 criteria will be used for evaluating
  software in this unit(Int 2)?
• What is the relationship between pseudocode and a
  structure diagram?
• Name 2 items of documentation usually provided
  with a software package, and describe what you
  would expect each one to contain.
• What 3 types of testing should be applied to any
  software?
• Describe 2 examples of maintenance that would be
  required on a game program.

129
Scope

• Variables can have 2 types of scope
• GLOBAL and LOCAL
• Global variables are created outside any subs,
  functions or procedures and can be used/seen by
  all subs/functions/procedures
• Local variables are created inside subs and can
  only be seen/used within that sub

130
Modularity

• Scope gives programmers freedom to create modules
  without worrying that they are creating variables
  in their module that conflict with the variables
  created by the other programmers
• E.g. we are creating a school management program.
  I am creating the module for pupils and I use the
  variable firstName. You are creating the module
  for the teachers and use a variable called
  firstName. As long as these variables are LOCAL
  to my sub, e.g. created within my sub there will
  be no conflict

131
Parameter Passing

• A parameter is just a variable being passed into
  a subroutine
• Very important programming concept
• Ensures variables dont interfere with each other
• Keeps programs reliable

132
Parameter Passing

• In real programming situations, several
  programmers are involved in the creation of the
  program
• The each create sub procedures
• Private sub valid_age(byval age as integer)

133
Parameter Passing

• Private sub valid_age(byval age as integer)
• To execute this sub procedure we would put the
  line
• Call valid_age(person_age)
• Note that the parameter passed does not match the
  variable, this is ok and will still work. As long
  as person_age is an integer
• This allows programmers to write procedures and
  not worry about what other programmers are
  calling variables

134
ByVal

• Used if you only need to use the value of the
  variable
• You wont be able to change the value of the
  variable
• You send a copy of it that is discarded after use
• Like giving someone a photocopy, they can write
  on it etc and throw it away after use, you keep
  the original

135
ByRef

• Used if you need to change the value of the
  variable
• They are passed in, updated and passed out for
  future use
• Like giving someone your master copy, if they
  change it and give you it back, the changes are
  permanent

136
Evidence
Int 2
Higher

• Task using Select Case (P20) Section 2
• Lucky Prize Draw P8 Section 4
• Book Orders Program Evaluation of Book Orders P
  24 Section 6 Testing
• Task 7.7.2 and 7.7.3 on page 17 section 7
• Task 7.8.2 on P23 section 7 User Guide
  Analysis Design

• Belindas Slab Calculator(P17)
• Blob diagram, Form Design, Pseudocode, Code
  listing, testing, User Guide
• Colour Changer(p59)
• Blob Diagram, Form Design, Pseudocode, Code
  listing, User Guide
• Times table program(P73)
• Code, UserGuide, Testing
• Any 2 of the following code listings
• Age Program, PIN program, Year Program (all on
  P94)