Visual Basic 2012 How to program (Sixth Edition) (Enhanced Class Average App)The
ID: 3801337 • Letter: V
Question
Visual Basic 2012 How to program (Sixth Edition)
(Enhanced Class Average App)The class average application of fig.4.12allowed the user to enter a set of grades then calculate anddisplay the total of the grades and the class average. Create anapp that enables the user to select a file in which to store grades.The app should allow the user to write any number of grades intothat file and it should write one grade per line. Next, modify theapp ofFig. 4.12to allow the user to specify the location and nameof a ±le containing grades. The app should read the grades fromthe file, then display the total of the grades and the classaverage
Explanation / Answer
Enhanced_Class_Average
Public Class Grades
Public Property Grades As String 'Strings grades entered
'constructor initializes grades
Public Sub New(ByVal grade As String)
Grades = grade ' calls Grades property Set accessor
End Sub
Public Property Grades() As Char
'initialize array of grades
Dim grades() As Grades = {
New Grade(
'displays grades entered
Dim Grades =
outputGradesEntered.AppendText(String>Format("{0}Grades only:{0}", vbCrLf
part 2
Imports System.IO ' using classes from this namespace
Public Class CreateGradesFolder
Dim fileWriter As StreamWriter ' writes grades to text files
' Creat a new file in which grades can be stored
Private Sub NewToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NewToolStripMenuItem.Click
' ensure that any prior file is closed
Dim result As DialogResult ' Stores result of Save dialog
Dim fileName As String ' Name of file to save data
Dim NumberOfGradesEntered As String 'Number of Grades to saved file
'display dialog so uer can choose the name of the file to save
Using fileChooser As New SaveFileDialog()
result = fileChooser.ShowDialog()
fileName = fileChooser.FileName ' get specified file name
End Using ' automatic call to fileChooser.Dispose() occurs here
' If user did not click Cancel
If result <> Windows.Forms.DialogResult.Cancel Then
Try
' open or create file for writing
fileWriter = New StreamWriter(fileName, True)
'Enable Contols
CloseToolStripMenuItem.Enabled = True
addFileName.Enabled = True
GradesTextBox.Enabled = True
NumberOfGradesEntered = True
Catch ex As IOEception
MessageBox.Show("Error Opening File", Error", MessageBoxButoons.Ok, MessageBoxIcon.Error)
End Try
End If
End Sub ' New ToolStripMenuItem_Click
' Add A File
Private Sub addFileButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles addFileButton.Click
'determines whether TextBox Grade field is empty
If GradeTextBox.Text <> String.Empty Then
'Try to store record to file
If GradeTextBox.Text <> String.Empty Then
Try
'gets file name
Dim FileName As Char
Convert.ToInt32(GradeTextBox.Text)
If GradeTextBox > 0 Then 'enter file name
'write file recor data to file separating filds by commas
fileWriter.WriteLine(accountNumber & "," &
GradesTextBox.Text
Convert.ToInt(NumberOfGradesEntered)
End If
Catch ex As Exception
End Try
End If
End If
End Sub
End Class
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