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Week 09 & 10
Week 08
Week 07
Week 05 & 06
Week 04
Week 03
Week 02
Week 01

Week 11

Objects
Any of the controls on a form are objects
Most of them have properties and methods
Buttons we draw on a form are objects
Created from classes
They are an instance of a class
Not all objects are visible

Classes
Are the blueprint or template used to create objects
There are many intrinsic classes in VB.net
You can create your own class

Object Oriented Programming
Is a way to program, it is a strategy
Allows use to reuse methods and code
Encapsulation: Let's use put all properties, methods, events into one package

Creating our own Class
You create the properties and methods
Properties are created using variables and data definitions
Methods are created using sub-procedures or functions

1- create class
2- add variables
3- add properties
4- add methods

1-
Public Class Booksale

End Class

2-
Private m_titleString As String
Private m_quantityInteger As Integer
Private m_priceDecimal As Decimal

3-
Public Property Title()As String
    Get
        Return m_titleString
    End Get
    Set(ByVal Value As String)
        m_titleString = Value
    End Set
End Property

4-
Public Function ExtPrice()As Decimal
    Return m_quantityInteger * m_priceDecimal
End Function

Constructors
You would create a constructor to intialize your object
You might open a connection to a database or set some properties
Sub New() is always the name of the constructor

'code in the form
mBookSale = New Booksale(titleTextbox.text, quanTextbox.text)
' this calls the Sub New sub-procedure in the class and
' passes it two values

'code in the class
Sub New(Title as String, Quantity as Interger)
    m_titleString = Title
    m_quantityInteger = Quantity
End Sub
'in this example the Sub New() takes the two
'values passed to it and sets the title property
'and the quantity property

Week 09 & 10

Select Case

' Determine the age and display the appropriate label
  Select Case ageInteger
    Case Is < 60
      displayLabel.Text = "Cold"
    Case 61 To 72
      displayLabel.Text = "Moderate"
    Case Else
      displayLabel.Text = "Hot"
  End Select

Case Is > 6
Case 300 to 600
Case 1, 3, 5, 7
Case “Pigs”
Case “Andy”, “Bob”
Case Else (optional)

Arrays
List or Series of values
When you need to store multiple values
List or series of values, like a combo or listbox BUT with no visual representation

Similar to a single variable
Dim scoresInteger(4) as Integer
Dim m_numbersInteger() as Integer = {1 , 3 , 5 , 7 , 9 , 11}
Dim animalsString() as String = {“Tiger”, “Elephant”, “Mouse”}

Dim scoresInteger(4) as Integer
       |          |         |
Array name        |     Data Type
      Index (subscript) 

Determining the size of an array
sizeArrayInteger = UBound(scoresInteger)

For Each Next Loop to look through an array (m_numbersInteger in this example)

Dim indNumInteger, totalNumbersInteger As Integer

For Each indNumInteger In m_numbersInteger
  totalNumbersInteger += indNumInteger
Next

lblD.Text = FormatNumber(totalNumbersInteger / counterInteger)

Structure

Used to collect different data types together
Person’s name, GPA and age

'Declarations area (module)
Structure Student
  Dim nameString As String
  Dim gpaDecimal As Decimal
  Dim ageInteger As Integer
End Structure

Dim m_indStudent As Student

'Local level
m_indStudent.nameString = nameTextbox.Text
m_indStudent.gpaDecimal = Cdec(gpaTextbox.Text)
m_indStudent.ageInteger = CInt(ageTextbox.Text)

Structure of an Array

'Declarations area (module)
Structure Student
  Dim nameString As String
  Dim gpaDecimal As Decimal
  Dim ageInteger As Integer
End Structure

Dim m_indStudents(20) As Student
Dim m_counterInteger as Integer

'Local level
m_indStudents(m_counterInteger).nameString = nameTextbox.Text
m_indStudents(m_counterInteger).gpaDecimal = Cdec(gpaTextbox.Text)
m_indStudents(m_counterInteger).ageInteger = CInt(ageTextbox.Text)

m_counterInteger += 1

Match in a ComboBox
'For Next loop to move through each item in productsComboBox
For countInteger = 0 To productsComboBox.Items.Count - 1
  If CStr(productsComboBox.Items(intCount)).ToUpper = productsComboBox.Text.ToUpper Then
    'if there is a match change
    'matchBoolean to true and exit loop
    matchBoolean = True
    Exit For
  End If
Next

'Check to see if there is a match
'if no match then add user input
If matchBoolean = False Then
  productsComboBox.Items.Add(productsComboBox.Text)
Else
  MessageBox.Show("This item already exists", "Error:Match", MessageBoxButtons.OK)
End If

Week 08

Multiple Forms
You can create a second form that is called from the original form

'code in the first form
aboutForm.Show() ' reveal the object

You can "push" information to the 2nd form from the 1st form
aboutForm.displayTextbox.text = "This is the 2nd form"

3 steps
Intialize counter
Increment counter
Test the counter

Intialize counter & Test the counter
         |
For LoopIndex = IntialValue To TestValue
  ‘Code
Next LoopIndex
         |
Increment counter

3 elements
LoopIndex : counter variable
InitialValue : value the counting(looping) starts at
TestValue : value that ends the looping

i.e.    

For countInteger = 0 To 7
  ' Code
Next countInteger

You can define the increments using Step

For countInteger = 0 To 7 Step 2
  ' Code (This loop will have 4 iterations)
Next

You can use variables for the end and step. You will need to Dim the variables

Dim countInteger, endInteger, stepInteger as Integer
endInteger = 7
stepInteger = 2

For countInteger = 0 To endInteger Step stepInteger
'Code
Next

For xInteger = 2 to 100 Step 2
For yInteger = stepInteger to endInteger Step stepInteger
For zInteger = 0 to fruitCombobox.Items.Count - 1
For dInteger = (X – 5) to mInteger
For yDecimal = 0.5D to 0.25D Step 0.05D
For sInteger = 10 to 0 Step -1

For countInteger = 0 To 6
will loop 7 times

For countInteger = 1 To 6
will loop 6 times

For countInteger = 0 To 6 Step 2
will loop 4 times

For countDecimal = 0 To 6 Step .5d
will loop 13 times

For countInteger = 6 To 0 Step -1
will loop 7 times

The IntialValue, TestValue and Step can be constants, variables, literals, expressions
You can not change TestValue and Step in the loop
The default Step is 1

To Uppercase
UCase(productsComboBox.Text)
UCase(CStr(productsComboBox.Items(countInteger)))

Week 07

List and Combo Boxes
  Controls for presenting the user a number of choices
  You can allow the user to add text
  Or restrict the user from adding text to the boxes

  Enter items into list boxes using the Items collection in the Properties window.
  Add and remove items in a list at run time.
  Determine which item in a list is selected.
  Use the Items.Count property to determine the number of items in a list.
  Display a selected item from a list.
  Use Do/Loops to iterate through a loop.

List box - User can NOT add text
List box - Control can be stretched to large size
Combo box - Has Drop Down Style property

Properties
  Items (Index Number)
  Text (combo box only)
  Sorted (set to true or false)
  Count (countInteger = moviesListBox.Items.Count)
  DropDownStyle (combo box only)
  Simple (User can add text, can be large)
  Drop Down (User can add text, is smaller)
  Drop Down List (User can NOT add text, is smaller)

Methods

Add (an entry into a ComboBox)
  fruitComboBox.Items.Add(entryTextbox.text)
  fruitComboBox.Items.Add(fruitString)
  fruitComboBox.Items.Add(fruitComboBox.Text)

Remove and RemoveAt (Remove an entry from the List or Combo Box)
  namesListBox.Items.Remove("Harold")
  statesComboBox.Items.Remove(statesComboBox.Text) 
  statesComboBox.Items.RemoveAt(statesComboBox.SelectedIndex)
  namesListBox.Items.RemoveAt(1)

Select (Highlight or display a specific entry)
  fruitComboBox.SelectedIndex = 3
  fruitComboBox.SelectedIndex = -1 (to deselect all items)

Clear (out all entries, very dramatic)
  namesListBox.Items.Clear()

To reference (a Combo or List Box entry)
  displayLabel.Text = fruitComboBox.Items(indexInteger)
  displayLabel.Text = fruitComboBox.Text

Do Loops
Used in relation to a condition

How many times will it loop?           \     The same question
How many times will it execute?     /
How many iterations will it have?   /

Do While Loops Pretest and Posttest

Do While X < 5
X = X + 1
Loop

Do
  X = X + 1
Loop While X < 5

Do Until Loops Pretest and Posttest

Do Until X = 7
  X = X + 1
Loop

Do
  X = X + 1
Loop Until X = 7

Loops end based on a condition YOU set
You are responsible for incrementing the counter
Post Tests have at least one iteration

Dim X as Integer
Do Until X = 3
  X = X + 1
Loop

Endless Loops
Do Until X > 7
  X = 1
Loop

Week 05 & 06

               Procedures
              /             \
Sub-procedures   Functions
Performs actions Performs actions
                       Returns a value

Where do you put procedures?
How do you call them?
Why use them?

Sub-procedures

This line of code within your code
Warning()

Calls this sub-procedure
Private Sub Warning()
               displayLabel.text = "Warning"
End Sub

Functions

  This line of code within your code...
commissionLabel.text = Commission(weeklySalesDecimal)
             ^                   ^                ^
value returned here      name         argument

  ...calls this function
                            Name       argument                return data type
                              |                |                            |
Private Function Commission(salesDecimal as Decimal) as Decimal
      Commission = salesDecimal * 0.15D
End Function

Private Function Commission(ByVal salesDecimal as Decimal) as Decimal

They return to where they left

Procedures can have arguments that are literal values, variables, or properties
displayLabel.text = Cal( 25 , intNumber , txtName.text)

Arguments
  Order
  Number of arguments
  Data Type
  (Name does not matter)

What are you passing in?
How are you manipulating it?
What are you returning?

You can return any data type in a function

You can use either of the following for a function
Commission = salesDecimal * 0.15D
Return salesDecimal * 0.15D

To create a procedure ask these questions
1. What is the procedure going to do?
2. What is it’s unique name?
3. Does it need any data?
4. Will it return any value?
5. What will the calculations be?
6. What will it’s logic be?
7. How and when do I call the procedures?

Note: make sure the menu property on the form is switched on

Dialog Boxes
Need to place on form from toolbox.
Need to name

Typical dialog boxes
Font
Color
Print
OpenFile
SaveFile
PrintPreview

the naming convention
colorDialog

 Code example:

' This code will open the dialog box for the user to choose a color
colorDialog.ShowDialog()

' This code applies the color property of the dialog
' box (the color the user chose) to the controls ForeColor property
displayLabel.ForeColor = colorDialog.Color

You can set initial values on a dialog box
dlgColor.Color = displayLabel.ForeColor

Note: Enabling a property during run time

Week 04

If Statements
If totalInteger=100 Then
  'code if the condition IS met
End If

If priceDecimal>25 Then
  'code if the condition IS met (TRUE)
Else
  'code if the condition is NOT met (FALSE)
End If

Relational Operators
=
>
<
>=
<=
<>

Nested If's
If tempInteger <=32 Then
  label = "Freezing"
Else
  If tempInteger > 80 Then
    label = "Hot"
  Else
    label = "Moderate"
  End If
End If

-OR- ElseIf

If tempInteger <=32 Then
  label = "Freezing"
Elseif tempInteger > 80 Then
  label = "Hot"
Else
  label = "Moderate"
End If

Note: If you use Elseif you only use ONE End If

Input Validation
You can validate information in a textbox

Number - Is the value a number
If IsNumeric(userAgeTextbox.text) Then

Range - Does the value fall within a range
If userAgeTextbox.text >0 AND userAgeTextbox.text <150 Then

Required field - Is the textbox filled out?
If userAgeTextbox.text <> "" Then

Debugging

Nesting

Compound Conditions
NOT
AND
OR

If varInteger > 0 AND varInteger < 10 Then
  'code if BOTH conditions are met
End If

If varInteger = 5 OR varInteger = 8 Then
  'code if EITHER condition is met
End If

If NOT varInteger = 2 Then
  'code if varInteger is not the value of 2
End If

If ___T___ And ___F___ Or ___T___ Then
        |                 |               |
         -------------               
                F                         T
                |                         |
                 ------------------
                            T

Message Box
MessageBox.Show("Text", "Title", [Button options])

Message Box Options
Buttons:
Ok (default)
Ok Cancel
Yes No
Yes No Cancel
-others-

Icons:
Exclamation
Warning
Error
Question
-others-

MessageBox.Show("Text", "Title", MessageBoxButtons.YesNo, MessageBoxIcon.Exclamation)

Radio Buttons : Use nested If's or If/ElseIf statements

If blueRadio.Checked = True Then
  testLabel.BackColor = Color.Blue
ElseIf greenRadio.Checked = True Then
  testLabel.BackColor = Color.Green
ElseIf yellowRadio.Checked = True Then
  testLabel.BackColor = Color.Yellow
End If

Checkboxes: Each Checkbox needs it's own If Statement

If fmCheckbox.Checked = True Then
  m_carPriceDecimal += 100
End If
If cdCheckbox.Checked = True Then
  m_carPriceDecimal += 50
End If
If mp3Checkbox.Checked = True Then
  m_carPriceDecimal += 25
End If

Note: You can assume that the condition is true in conditionals
If radioCheckbox.checked = "true" Then
- is the same as -
If radioCheckbos.checked Then

Expand Plan Solution step

1. Define Problem
2. Plan solution
1. What is your input?
2. What is your output?
3. Objects
4. Events to recognize
5. Calculations
6. Variables
7. Constants
3. Design interface
4. Code and Comment(Pseudo Code)
5. Debug