2006 FINAL PRACTICE PROBLEMS ANSWERS

1. ' Assume that Painter is the default radio button. 
   Public Sub btnSubmit_Click(...) Handles btnSubmit.Click
       If radElectrician.Value Then
           txtTotal.Text = txtHoursWorked.Text * 85
       ElseIf radPlumber.Value Then
           txtTotal.Text = txtHoursWorked.Text * 75
       Else
           txtTotal.Text = txtHoursWorked.Text * 40
       End If
   End Sub

2. Variable Trace Table:    Output:
     x     y                        100
   -----+-----                      41
    150   100                       17
     50    16                       4
     16    25
      5    12
      1     3

3. Assumption (a): One word per line.
   Public Sub btnSubmit_Click(...) Handles btnSubmit.Click
      Dim line As String
      Dim count As Integer = 0
      Dim sr As New StreamReader("words.txt")
      While sr.Peek( ) > -1
          line = sr.ReadLine( )
          If line.Length = 4 Then
              count += 1
          End If
      End While
      sr.Close( )
   End Sub

   Assumption (b): Multiple space delimited words per line.
   Public Sub btnSubmit_Click(...) Handles btnSubmit.Click
      Dim line, fields( ), word As String
      Dim count As Integer = 0
      Dim sr As New StreamReader("words.txt")
      While sr.Peek( ) > -1
          line = sr.ReadLine( )
          fields = Split(line, " ")
          For Each word in fields
              If word.Length = 4 Then
                  count += 1
              End If
          Next
      End While
      sr.Close( )
   End Sub

4. Public Function ReplaceSpaces(s As String) As String
       Dim t As String = ""
       Dim c As String
       Dim i As Integer
       For i = 0 To s.Length - 1
           c = s.Substring(i, 1)
           If c = " " Then
               t &= "*"
           Else
               t &= c
           End If
       Next
       Return t
   End Function

   Public Sub Main( )
       Dim s = "test line"
       WriteLine(s & " " & ReplaceStrings(s))
       s = "   "  'Three spaces.
       WriteLine(s & " " & ReplaceStrings(s))
   End Sub

5. Private c As New OleDbConnection
   Private sc As OleDbCommand
   Private da As New OleDbDataAdapter
   Private ds As New Dataset 

   Public Sub Form1_Load(...) Handles MyBase.Load
       c.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;" & _
          "Data Source=c:\Database\grades.mdb"
       c.Open( )
       sc = c.CreateCommand()
       sc.CommandType = CommandType.Text
       sc.CommandText = "SELECT Name FROM GradeData WHERE Grade = 'A'"
       da.SelectCommand = c
       Dim n As Integer = da.Fill(ds, "GradeData")
       Dim i As Integer
       For i = 0 To n - 1
           lstNames.Items.Add(ds.Tables(0).Rows(i).Item(0)
       Next   
   End Sub

6. Public Sub Main( )
      Dim i As Integer
      Dim r As New Random
      For i = 1 To 1000
          WriteLine(r.Next(0, 2))
      Next
   End Sub

7. Public Sub picDisplay_Paint(...) Handles picDisplay.Paint
      Dim g As Graphics = e.Graphics
      Dim rb As New SolidBrush(Color.Red)
      Dim wb As New SolidBrush(Color.White)
      Dim gb As New SolidBrush(Color.Blue)
      g.FillEllipse(rb, 60, 60, 80, 80)
      g.FillEllipse(wb, 170, 270, 60, 60)
      g.FillEllipse(bb, 280, 280, 40, 40)
   End Sub