451207 Information Systems and Programming

1
451-207 Information Systems and Programming

• Allison Kealy
• akealy_at_unimelb.edu.au
• Department of Geomatics
• The University of Melbourne Victoria
• 3010

2
VB Course Plan
Week 1 Introduction to Visual Basic
Week 2 Decisions and Repetitions
Week 3 Functions and Subroutines
Week 4 Arrays and other applications
3
What we will cover today!

• Visual Basic data types
• Relational and logical operators in Visual Basic
• How Visual Basic assigns control in a program

4
At the end of todays lecture .

• You should be able to
• assign values/information to different variable
  types
• code arithmetic operations
• Control the execution flow within a Visual Basic
  program

5
Data Types

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Numbers
• Dim interestRate As Single
• Dim range As Double
• Dim age As Integer
• ,-,/,,
• Strings
• Dim phrase As String

Dim variable name As variable type
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Relational Operators

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• A condition is an expression involving relational
  operators that is either true or false

7
Class Activity

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Determine whether the following are true or false
• 1 lt 1
• car lt cat
• 1lt1
• If a4 and b3 (ab)lt2a

8
Logical Operators

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• More complex situations are normally required ie
  (2ltn) And (nlt5)
• cond1 And cond2
• cond1 Or cond2
• Not cond1

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Class Activity

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Determine whether the following are true or false
  if n has a value of 4 and the string variable
  answ has a value Y
• (2ltn) And (nlt6)
• (2ltn) Or (n6)
• Not (Nlt6)
• (answY) And (answ y)

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Control Structures

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Control structures control the flow of execution
  in a program or function.
• Visual Basic control structures allow you to
  combine individual instructions into a single
  logical unit with one entry point and one exit
  point.
• Instructions are organised into three kinds of
  control structures to control execution flow
  sequence, selection and repetition.

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Sequence

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Until now we have only been using sequential flow

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Selection

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• A selection control structure chooses which
  alternative to execute.
• A program chooses between alternative suggestions
  by testing the value of key variables.
• A condition is an expression that is either false
  or true. It establishes a criterion for either
  executing or skipping a group of statements.

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If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• An If Block allows a program to decide on a
  course of action based on whether a certain
  condition is true or false
• The if statement is the primary selection control
  structure.

If condition Then action 1 Else action
2 End If
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If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

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Example If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Task Write a program to find the larger of two
numbers input by the user.
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Example If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• What is the problem asking us to do?

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and document
17
Class Activity If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Problem Inputs
• Problem Outputs

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and document
18
Class Activity If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Get the data
• Perform the computations
• Display the results

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and document
19
Class Activity If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
20
Class Activity If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
21
Class Activity If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Test the program for all cases. What test cases
would you use?
Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
22
Class Activity If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Include some documentation in the code you have
just written
Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
23
Nested If Blocks

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

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If Blocks and Logical Operators

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

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Repetition

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• A repetition structure allows the programmer to
  specify that an action is to be repeated until
  some terminating condition occurs.
• The repetition of steps in a program is called a
  loop.

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Repetition

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

No
No loop required
Any steps repeated
Yes
No
Know in advance how many times to repeat
Do loops
Yes
Use a for loop
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Do Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Repeats a sequence of statements either as long
  as or until a certain condition is true

Do while condition statements Loop
Do statements Loop Until Condition
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Example

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Task Write a program that displays the numbers 1
through 10.
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Class Activity Do Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• What is the problem asking us to do?

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and document
30
Class Activity Do Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Problem Inputs
• Problem Outputs

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and document
31
Class Activity Do Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Get the data
• Perform the computations
• Display the results

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and document
32
Class Activity Do Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
33
Class Activity Do Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
34
Class Activity Do Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Test the program for all cases. What test cases
would you use?
Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
35
Class Activity Do Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Include some documentation in the code you have
just written
Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
36
For Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• When we know exactly how many times a loop should
  be executed as opposed to until a condition is
  met as in the do loop

For i m to n Step s statements Next m
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Example For Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Task Suppose the population of a city is 300,000
in the year 1998 and is growing at the rate of 3
per year. Display a table showing the population
of each year until 2002
38
Class Activity For Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• What is the problem asking us to do?

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and document
39
Class Activity For Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Problem Inputs
• Problem Outputs

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and document
40
Class Activity For Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

• Get the data
• Perform the computations
• Display the results

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and document
41
Class Activity For Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
42
Class Activity For Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
43
Class Activity For Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Test the program for all cases. What test cases
would you use?
Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
44
Class Activity For Loops

• Visual Basic Data Types
• Relational Operators
• Logical Operators
• Control Structures
• Sequence
• Selection
• Repetition

Include some documentation in the code you have
just written
Specify the problem requirements Analyse the
problem Design the algorithm to solve the
problem Choose the interface Implement the
algorithm Test and verify the completed
program Maintain and documentation
45
Class Activity

• Task
• Write a program that requests the user to enter a
  number n, from 1 to 30 and one of the letters S
  or P. Then calculate the sum of product of the
  numbers from 1 to n depending upon whether S or P
  was selected.

46
VB Course Plan
Week 1 Introduction to Visual Basic
Week 2 Decisions and Repetitions
Week 3 Functions and Subroutines
Week 4 Arrays and other applications