ListBox Searching

• Download source code - 7.4 Kb
• Download demo project - 7.2 Kb

Introduction

This code shows you how to search through a ListBox (ListBox1) and add all Items that match the search query (from TextBox1) to a second ListBox (ListBox2).

Using The Source Code

I have included two sets of the source code, one with comments, and one without.  I did this because the begginers have a better chance of needed comments to walk them through the steps, but they might just be more in the way than anything else for the more advanced programmers.

The Source Code

 
Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
  Handles btnSearch.Click
      '//removes all items from the second List Box
    ListBox2.Items.Clear()
      '//gets the total number of items in the first ListBox
    Dim listLength As Integer = (ListBox1.Items.Count - 1)
      '//i -> counter through loops : j -> counter through chars in string
    Dim i, j As Integer
      '//listString -> string of item in ListBox1
      '//newString -> gets added to one char at a time from listString 
    Dim listString, newString As String
'//self explanitory, lol
    If radioFull.Checked = True Then
          '//loop through all items in ListBox1
        For i = 0 To listLength
              '//one at a time in sequential order
            listString = ListBox1.Items.Item(i)
              '//searches ListBox1 Item for the text in TextBox1
              '//turning all text to lowercase
            If InStr(listString.ToLower, TextBox1.Text.ToLower) Then
                  '//if text is found then add ListBox1 Item to ListBox2
                ListBox2.Items.Add(listString)
            End If
        Next
'//search Item Index
    ElseIf radioIndex.Checked = True Then
        For i = 0 To listLength
            listString = ListBox1.Items.Item(i)
              '//loop through listString 1 char at a time
            For j = 0 To listString.Length - 1
                  '//goes through first If until you get to a Space Char
                  '//if char is NOT Space Char then
                If listString.Substring(j, 1) <> Chr(32) Then
                      '//add char to newString
                    newString += listString.Substring(j, 1)
                Else  '//once you get to a Space Char
                      '//searches ListBox1 Item for the text in TextBox1
                    If InStr(newString, TextBox1.Text) Then
                          '//add Item to ListBox2
                        ListBox2.Items.Add(ListBox1.Items.Item(i))
                    End If
                      '//Exit For Statement
                    Exit For
                End If
            Next
              '//empties newString for the next round!
            newString = Nothing
              '//time to search next Item in ListBox1
        Next
'//search Text, non Case Sensative
    ElseIf radioText.Checked = True Then
          '//holds number of Space Chars
        Dim spaceCharCounter As Integer = 0
        For i = 0 To listLength
            listString = ListBox1.Items.Item(i)
              '//go through Item 1 char at a time
            For j = 0 To listString.Length - 1
                  '//if spaceCharCounter is greater than or equal to 2
                If spaceCharCounter >= 2 Then
                      '//add Char to newString
                    newString += listString.Substring(j, 1)
                      '//if char in listString = Space Char
                ElseIf listString.Substring(j, 1) = Chr(32) Then
                      '//add 1 to spaceCharCounter
                    spaceCharCounter += 1
                End If
                  '//next Char in ListBox1 Item
            Next
              '//search with all lowercase
            If InStr(newString.ToLower, TextBox1.Text.ToLower) Then
                  '//add Item to ListBox2
                ListBox2.Items.Add(ListBox1.Items.Item(i))
            End If
              '//delete values
            listString = Nothing
            spaceCharCounter = 0
            newString = Nothing
              '//search next Item in ListBox1
        Next
'//search Text, Case Sensative
    ElseIf radioAdvText.Checked = True Then
        Dim spaceCharCounter As Integer = 0
        For i = 0 To listLength
            listString = ListBox1.Items.Item(i)
            For j = 0 To listString.Length - 1
                If spaceCharCounter >= 2 Then
                    newString += listString.Substring(j, 1)
                ElseIf listString.Substring(j, 1) = Chr(32) Then
                    spaceCharCounter += 1
                End If
            Next
              '//***The one difference between the last 2 radio buttons
              '//***There is NO .ToLower in search function
            If InStr(newString, TextBox1.Text) Then
                ListBox2.Items.Add(ListBox1.Items.Item(i))
            End If
            listString = Nothing
            spaceCharCounter = 0
            newString = Nothing
        Next
    End If
    listString = Nothing
End Sub
 

Now without the comments.

Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
  Handles btnSearch.Click
    ListBox2.Items.Clear()
    Dim listLength As Integer = (ListBox1.Items.Count - 1)
    Dim i, j As Integer
    Dim listString, newString As String
    If radioFull.Checked = True Then
        For i = 0 To listLength
            listString = ListBox1.Items.Item(i)
            If InStr(listString.ToLower, TextBox1.Text.ToLower) Then
                ListBox2.Items.Add(listString)
            End If
        Next
    ElseIf radioIndex.Checked = True Then
        For i = 0 To listLength
            listString = ListBox1.Items.Item(i)
            For j = 0 To listString.Length - 1
                If listString.Substring(j, 1) <> Chr(32) Then
                    newString += listString.Substring(j, 1)
                Else
                    If InStr(newString, TextBox1.Text) Then
                        ListBox2.Items.Add(ListBox1.Items.Item(i))
                    End If
                Exit For
                End If
            Next
            newString = Nothing
        Next
    ElseIf radioText.Checked = True Then
        Dim spaceCharCounter As Integer = 0
        For i = 0 To listLength
            listString = ListBox1.Items.Item(i)
            For j = 0 To listString.Length - 1
                If spaceCharCounter >= 2 Then
                    newString += listString.Substring(j, 1)
                ElseIf listString.Substring(j, 1) = Chr(32) Then
                    spaceCharCounter += 1
                End If
            Next
            If InStr(newString.ToLower, TextBox1.Text.ToLower) Then
                ListBox2.Items.Add(ListBox1.Items.Item(i))
            End If
            listString = Nothing
            spaceCharCounter = 0
            newString = Nothing
        Next
    ElseIf radioAdvText.Checked = True Then
        Dim spaceCharCounter As Integer = 0
        For i = 0 To listLength
            listString = ListBox1.Items.Item(i)
            For j = 0 To listString.Length - 1
                If spaceCharCounter >= 2 Then
                    newString += listString.Substring(j, 1)
                ElseIf listString.Substring(j, 1) = Chr(32) Then
                    spaceCharCounter += 1
                End If
            Next
            If InStr(newString, TextBox1.Text) Then
                ListBox2.Items.Add(ListBox1.Items.Item(i))
            End If
            listString = Nothing
            spaceCharCounter = 0
            newString = Nothing
        Next
    End If
    listString = Nothing
End Sub

The End

I would have seperated the different RadioButton.Checked statements for easier reading, but I'm having some problems with the editor.

Have Fun!