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Chapter 6

Chapter 6 . Arrays, Random, Functions, Subroutines. Application #1. Global and Form loads. Public Class EnhancedCafeteriaSurvey ' two-dimensional array stores voting results Dim votes(3, 1) As Integer ' handles Form's Load event

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Chapter 6

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  1. Chapter 6 Arrays, Random, Functions, Subroutines

  2. Application #1

  3. Global and Form loads PublicClassEnhancedCafeteriaSurvey ' two-dimensional array stores voting results Dim votes(3, 1) AsInteger ' handles Form's Load event PrivateSubEnhancedCafeteriaSurvey_Load(ByVal sender AsSystem.Object, ByVal e AsSystem.EventArgs) HandlesMyBase.Load foodsComboBox.SelectedIndex = 0 ' select first food in list EndSub' EnhancedCafeteriaSurvey_Load

  4. ' handles Vote Button's Click event PrivateSubvoteButton_Click(ByVal sender AsSystem.Object, ByVal e AsSystem.EventArgs) HandlesvoteButton.Click Dim index AsInteger = foodsComboBox.SelectedIndex ' count the vote IflikeRadioButton.Checked = TrueThen votes(index, 0) += 1 Else votes(index, 1) += 1 EndIf DisplayVotes() ' display the voting results EndSub' voteButton_Click ' display the voting results in the ListBox SubDisplayVotes() resultsListBox.Items.Clear() ' clear the previous results ' display the ListBox header resultsListBox.Items.Add("Menu Item" & vbTab & "Like" & vbTab & "Dislike") ' add voting results for each food option For counter AsInteger = 0 Tovotes.GetUpperBound(0) resultsListBox.Items.Add( foodsComboBox.Items(counter).ToString() & vbTab & votes(counter, 0) & vbTab & votes(counter, 1)) Next EndSub' DisplayVotes Function call

  5. ' display the voting results in the ListBox SubDisplayVotes() resultsListBox.Items.Clear() ' clear the previous results ' display the ListBox header resultsListBox.Items.Add("Menu Item" & vbTab & "Like" & vbTab & "Dislike") ' add voting results for each food option For counter AsInteger = 0 Tovotes.GetUpperBound(0) resultsListBox.Items.Add( foodsComboBox.Items(counter).ToString() & vbTab & votes(counter, 0) & vbTab & votes(counter, 1)) Next EndSub' DisplayVotes

  6. Application #2

  7. PublicClassGuessTheNumber DimrandomObjectAsNewRandom() Dim number AsInteger = randomObject.Next(1, 101) ' handles Enter button click event PrivateSubenterButton_Click(ByVal sender AsSystem.Object, ByVal e AsSystem.EventArgs) HandlesenterButton.Click ' retrieve the user's guess Dim guess AsInteger = Convert.ToInt32(guessTextBox.Text) ' check answer If guess = number Then outputLabel.Text = "Correct!" enterButton.Enabled = False newGameButton.Enabled = True ElseIf guess > number Then outputLabel.Text = "Too high..." Else outputLabel.Text = "Too low..." EndIf guessTextBox.Focus() ' give focus to the TextBox EndSub' enterButton_Click

  8. PrivateSubnewGameButton_Click(ByVal sender AsSystem.Object, ByVal e AsSystem.EventArgs) HandlesnewGameButton.Click ' start a new game number = randomObject.Next(1, 101) ' generate new number enterButton.Enabled = True' enable the Enter Button newGameButton.Enabled = False' disable the New Game Button outputLabel.Text = ""' clear result guessTextBox.Clear() ' clear the previous guess guessTextBox.Focus() EndSub' newGameButton_Click ' handles Guess TextBox'sTextChanged event PrivateSubguessTextBox_TextChanged(ByVal sender AsSystem.Object, ByVal e AsSystem.EventArgs) HandlesguessTextBox.TextChanged outputLabel.Text = String.Empty' clear result EndSub' guessTextBox_TextChanged

  9. PublicClassRoadSignTest ' String array stores sign names Dim options() AsString = { "Do Not Enter", "Narrow bridge", "No bicycles", "No left turn", "No Pedestrians", "No U-turn", "Road Narrows", "Stop", "Stop sign ahead", "Traffic signals ahead", "Winding road ahead", "Yield"} ' Boolean array tracks displayed signs Dim used(options.GetUpperBound(0)) AsBoolean Dim count AsInteger = 1 ' number of signs shown DimcorrectAnswerAsInteger' index of current sign ' handles Road Sign Test Form's Load event PrivateSubRoadSignTest_Load(ByVal sender AsSystem.Object, ByVal e AsSystem.EventArgs) HandlesMyBase.Load Array.Sort(options) ' alphabetize sign names ' display sign names in ComboBox optionsComboBox.DataSource = options DisplaySign() ' display first sign in PictureBox EndSub' RoadSignTest_Load

  10. ' display random sign in PictureBox SubDisplaySign() ' unique index ensures that a sign is used no more than once correctAnswer = GetUniqueRandomNumber() ' retrieve specific image from resources DimpictureResource = My.Resources.ResourceManager.GetObject("sign" & correctAnswer) signPicture.Image = CType(pictureResource, Image) ' display image EndSub' DisplaySign FunctionGetUniqueRandomNumber() AsInteger DimrandomObjectAsNewRandom() DimrandomNumberAsInteger Do' generate random numbers until unused sign is found randomNumber = randomObject.Next(0, used.Length) LoopUntil used(randomNumber) = False ' indicate that sign has been used used(randomNumber) = True ReturnrandomNumber' return index for new sign EndFunction' GetUniqueRandomNumber

  11. ' handles Submit Button's Click event PrivateSubsubmitButton_Click(ByVal sender AsSystem.Object, ByVal e AsSystem.EventArgs) HandlessubmitButton.Click ' retrieve answer from ComboBox Dim response AsString = Convert.ToString(optionsComboBox.SelectedValue) ' verify answer If response = options(correctAnswer) Then feedBackLabel.Text = "Correct!" Else feedBackLabel.Text = "Incorrect." EndIf ' inform user if test is over If count >= 5 Then' test is over feedBackLabel.Text &= " Done!" nextButton.Enabled = False submitButton.Enabled = False optionsComboBox.Enabled = False Else' test is not over submitButton.Enabled = False nextButton.Enabled = True EndIf EndSub' submitButton_Click

  12. ' handles Next Sign Button's Click event PrivateSubnextButton_Click(ByVal sender AsSystem.Object, ByVal e AsSystem.EventArgs) HandlesnextButton.Click DisplaySign() ' display next sign feedBackLabel.Text = String.Empty' clear output ' change selected sign to first in ComboBox optionsComboBox.SelectedIndex = 0 count += 1 ' update number of signs shown submitButton.Enabled = True nextButton.Enabled = False EndSub' nextButton_Click EndClass' RoadSignTest

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