Home > Visual Basic Language > how can I string search my listbox entries to avoid duplicate entries in VB 2008

how can I string search my listbox entries to avoid duplicate entries in VB 2008

I have a program where you have three entries, CD name, artist, price and it goes into a listbox and .txt file when closing. I have to have a message box if you enter the same CD name. I have a code to open the .txt file and compare strings but I need to change it to compare only the CD name and not all three entries. Is there a way to do my string compare against my listbox without opening the .txt file?? The program loads the listbox from the .txt file when opening.

    Private Sub btnAdd_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        ' adds CD information to the list box

        ' declare variables
        Dim strName As String
        Dim strArtist As String
        Dim strPrice As String
        Dim strConcatenatedInfo As String
        Dim dblPrice As Double

        'get the CD information
        strName = InputBox("CD name:", "CD Collection")
        strArtist = InputBox("Artist:", "CD Collection")
        strPrice = InputBox("Price:", "CD Collection")

        'format the price, then concatenate the
        'input items, using 48 spaces for the 
        'CD name, 32 spaces for the artist name,
        'and 5 spaces for the price
        Double.TryParse(strPrice, dblPrice)
        strPrice = dblPrice.ToString("N2")
        strConcatenatedInfo = strName.PadRight(48) & _
        strArtist.PadRight(32) & strPrice.PadLeft(5)

        'check to see if CD already exists
        ' declare variables
        Dim infile As IO.StreamReader
        Dim strInfo As String

        Dim blnIsValid As Boolean = True 'to add CD to list if not already in file

        'verify that the file exists 
        If IO.File.Exists("CDs.txt") Then
            'open the file for input 
            infile = IO.File.OpenText("CDs.txt")
            'process loop instructions until end of file 
            Do Until infile.Peek = -1
                'read a line from the file
                strInfo = infile.ReadLine

                If strConcatenatedInfo.ToUpper Like strInfo.ToUpper Then 'to.upper to compare strings regardless of capitals
                    blnIsValid = False
                    MessageBox.Show("CD already in file", _
                      "CD Collection", MessageBoxButtons.OK, MessageBoxIcon.Information)
                End If

            Loop
            'close the file 
            infile.Close()
            'select the first item in the list box 
            lstCds.SelectedIndex = 0
        Else
            MessageBox.Show("Can't find the CDs.txt file", _
            "CD Collection", MessageBoxButtons.OK, MessageBoxIcon.Information)
        End If

        'add the information to the list box if not on list
        If blnIsValid = True Then
            lstCds.Items.Add(strConcatenatedInfo)
        End If

        ' save the list box information

        ' declare a StreamWriter variable
        Dim outFile As IO.StreamWriter

        ' open the file for output
        outFile = IO.File.CreateText("CDs.txt")

        ' write each line in the list box
        For intIndex As Integer = 0 To lstCds.Items.Count - 1
            outFile.WriteLine(lstCds.Items(intIndex))
        Next intIndex

        ' close the file
        outFile.Close()
    End Sub

Nice_Guy Sunday, November 29, 2009 10:28 PM

I think you are wanting to maketwo changes -
1. Compare the file name only
2. Compare the text box entry to the list box item, not to the text file lines.

To compare the name only, use strName, not strConcatenatedInfo. For instance:

If Trim(strName.ToUpper) = Trim(strInfo.ToUpper) Then ...

However, without knowing the exact format of the text file lines, it's not possible to predict whether or not that will work. For the list box, the format of the lines is known - the name will be in the first 48 characters, because that's how the list box item was built.

To compare to the list box rather than the file, replace the file read loop with a list box items loop:

For Each strInfo As String in lstCDs.Items
    If Trim(strName.ToUpper) = _
            Trim(strInfo.ToUpper.SubString(0,48)) Then 
        blnIsValid = False
        MessageBox.Show("CD already in file", _
            "CD Collection", MessageBoxButtons.OK, _
            MessageBoxIcon.Information)
    End If
Next

Marked As Answer byNice_Guy Monday, November 30, 2009 12:35 AM

Acamar Sunday, November 29, 2009 11:25 PM

First thanks, the for/ next statement you gave meworks as needed but now when I try to add a new CD it will not populate the list box as before. I added an if statement for the next two messageboxentries, artist and price so they only come up if there is no name match. Could it be where I placed the for/next statement?
I'll list the whole code & txt file this time.

CDs.txt file:
A Little Bit Longer                             Jonas Brothers                  12.50
At Folsom Prison                                Johnny Cash                     11.99
Covers                                          James Taylor                    11.99
Funhouse                                        Pink                             8.99
High School Musical 3: Senior Year              Original Soundtrack             12.99
Jennifer Hudson                                 Jennifer Hudson                 12.99
Lucky Ols Sun                                   Kenny Chesney                    9.99
Soul                                            Seal                            10.99
test                                            Bozo                           4.99

code:

Option Explicit On
Option Strict On
Option Infer Off

Public Class frmMain

    Private Sub btnExit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnExit.Click
        Me.Close()
    End Sub

    Private Sub frmMain_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        ' save the list box information

        ' declare a StreamWriter variable
        Dim outFile As IO.StreamWriter

        ' open the file for output
        outFile = IO.File.CreateText("CDs.txt")

        ' write each line in the list box
        For intIndex As Integer = 0 To lstCds.Items.Count - 1
            outFile.WriteLine(lstCds.Items(intIndex))
        Next intIndex

        ' close the file
        outFile.Close()
    End Sub

    Private Sub frmMain_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        ' fills the list box with data 
        ' stored in a sequential access file

        ' declare variables
        Dim infile As IO.StreamReader
        Dim strInfo As String

        'verify that the file exists 
        If IO.File.Exists("CDs.txt") Then
            'open the file for input 
            infile = IO.File.OpenText("CDs.txt")
            'process loop instructions until end of file 
            Do Until infile.Peek = -1
                'read a line from the file
                strInfo = infile.ReadLine
                'add the line to the list box
                lstCds.Items.Add(strInfo)
            Loop
            'close the file 
            infile.Close()
            'select the first item in the list box 
            lstCds.SelectedIndex = 0
        Else
            MessageBox.Show("Can't find the CDs.txt file", _
            "CD Collection", MessageBoxButtons.OK, MessageBoxIcon.Information)
        End If


    End Sub
 

    Private Sub btnAdd_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        ' adds CD information to the list box

        ' declare variables
        Dim strName As String
        Dim strArtist As String
        Dim strPrice As String
        Dim strConcatenatedInfo As String
        Dim dblPrice As Double
        Dim blnIsValid As Boolean = True 'to add CD to list if not already in file
        'get the CD information


        strName = InputBox("CD name:", "CD Collection")
        For Each strInfo As String In lstCds.Items
            If Trim(strName.ToUpper) = _
                    Trim(strInfo.ToUpper.Substring(0, 48)) Then
                blnIsValid = False
                MessageBox.Show("CD already in file", _
                    "CD Collection", MessageBoxButtons.OK, _
                    MessageBoxIcon.Information)
            End If
        Next

        If blnIsValid = True Then
            strArtist = InputBox("Artist:", "CD Collection")
            strPrice = InputBox("Price:", "CD Collection")

            'format the price, then concatenate the
            'input items, using 48 spaces for the 
            'CD name, 32 spaces for the artist name,
            'and 5 spaces for the price
            Double.TryParse(strPrice, dblPrice)
            strPrice = dblPrice.ToString("N2")
            strConcatenatedInfo = strName.PadRight(48) & _
            strArtist.PadRight(32) & strPrice.PadLeft(5)
        End If


    End Sub

    Private Sub btnRemove_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnRemove.Click
        'removes the selected line from the list box

        'if a line is selected, remove the line
        If lstCds.SelectedIndex <> -1 Then
            lstCds.Items.RemoveAt(lstCds.SelectedIndex)
        End If
    End Sub

    Private Sub lstCds_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstCds.SelectedIndexChanged

    End Sub
End Class

Marked As Answer byNice_Guy Monday, November 30, 2009 12:35 AM

Nice_Guy Monday, November 30, 2009 12:20 AM

I found my populate error I deleted my line to add to list box.

thanks again!!!!!!!!!

Marked As Answer byNice_Guy Monday, November 30, 2009 12:35 AM

Nice_Guy Monday, November 30, 2009 12:35 AM

For Each strInfo As String in lstCDs.Items
    If Trim(strName.ToUpper) = _
            Trim(strInfo.ToUpper.SubString(0,48)) Then 
        blnIsValid = False
        MessageBox.Show("CD already in file", _
            "CD Collection", MessageBoxButtons.OK, _
            MessageBoxIcon.Information)
    End If
Next

Marked As Answer byNice_Guy Monday, November 30, 2009 12:35 AM

Acamar Sunday, November 29, 2009 11:25 PM

CDs.txt file:
A Little Bit Longer                             Jonas Brothers                  12.50
At Folsom Prison                                Johnny Cash                     11.99
Covers                                          James Taylor                    11.99
Funhouse                                        Pink                             8.99
High School Musical 3: Senior Year              Original Soundtrack             12.99
Jennifer Hudson                                 Jennifer Hudson                 12.99
Lucky Ols Sun                                   Kenny Chesney                    9.99
Soul                                            Seal                            10.99
test                                            Bozo                           4.99

code:

Option Explicit On
Option Strict On
Option Infer Off

Public Class frmMain

    Private Sub btnExit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnExit.Click
        Me.Close()
    End Sub

    Private Sub frmMain_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        ' save the list box information

        ' declare a StreamWriter variable
        Dim outFile As IO.StreamWriter

        ' open the file for output
        outFile = IO.File.CreateText("CDs.txt")

        ' write each line in the list box
        For intIndex As Integer = 0 To lstCds.Items.Count - 1
            outFile.WriteLine(lstCds.Items(intIndex))
        Next intIndex

        ' close the file
        outFile.Close()
    End Sub

    Private Sub frmMain_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        ' fills the list box with data 
        ' stored in a sequential access file

        ' declare variables
        Dim infile As IO.StreamReader
        Dim strInfo As String

        'verify that the file exists 
        If IO.File.Exists("CDs.txt") Then
            'open the file for input 
            infile = IO.File.OpenText("CDs.txt")
            'process loop instructions until end of file 
            Do Until infile.Peek = -1
                'read a line from the file
                strInfo = infile.ReadLine
                'add the line to the list box
                lstCds.Items.Add(strInfo)
            Loop
            'close the file 
            infile.Close()
            'select the first item in the list box 
            lstCds.SelectedIndex = 0
        Else
            MessageBox.Show("Can't find the CDs.txt file", _
            "CD Collection", MessageBoxButtons.OK, MessageBoxIcon.Information)
        End If


    End Sub
 

    Private Sub btnAdd_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        ' adds CD information to the list box

        ' declare variables
        Dim strName As String
        Dim strArtist As String
        Dim strPrice As String
        Dim strConcatenatedInfo As String
        Dim dblPrice As Double
        Dim blnIsValid As Boolean = True 'to add CD to list if not already in file
        'get the CD information


        strName = InputBox("CD name:", "CD Collection")
        For Each strInfo As String In lstCds.Items
            If Trim(strName.ToUpper) = _
                    Trim(strInfo.ToUpper.Substring(0, 48)) Then
                blnIsValid = False
                MessageBox.Show("CD already in file", _
                    "CD Collection", MessageBoxButtons.OK, _
                    MessageBoxIcon.Information)
            End If
        Next

        If blnIsValid = True Then
            strArtist = InputBox("Artist:", "CD Collection")
            strPrice = InputBox("Price:", "CD Collection")

            'format the price, then concatenate the
            'input items, using 48 spaces for the 
            'CD name, 32 spaces for the artist name,
            'and 5 spaces for the price
            Double.TryParse(strPrice, dblPrice)
            strPrice = dblPrice.ToString("N2")
            strConcatenatedInfo = strName.PadRight(48) & _
            strArtist.PadRight(32) & strPrice.PadLeft(5)
        End If


    End Sub

    Private Sub btnRemove_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnRemove.Click
        'removes the selected line from the list box

        'if a line is selected, remove the line
        If lstCds.SelectedIndex <> -1 Then
            lstCds.Items.RemoveAt(lstCds.SelectedIndex)
        End If
    End Sub

    Private Sub lstCds_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstCds.SelectedIndexChanged

    End Sub
End Class

Marked As Answer byNice_Guy Monday, November 30, 2009 12:35 AM

Nice_Guy Monday, November 30, 2009 12:20 AM

I found my populate error I deleted my line to add to list box.

thanks again!!!!!!!!!

Marked As Answer byNice_Guy Monday, November 30, 2009 12:35 AM

Nice_Guy Monday, November 30, 2009 12:35 AM

You have somehow lost the lines that add the concatenated string to the list box. Originally it was

        If blnIsValid = True Then
            lstCds.Items.Add(strConcatenatedInfo)
        End If

so you have to include the Add line in the True branch of the new blnIsValid test. It becomes:

    '...
    Double.TryParse(strPrice, dblPrice)
    strPrice = dblPrice.ToString("N2")
    strConcatenatedInfo = strName.PadRight(48) & _
    strArtist.PadRight(32) & strPrice.PadLeft(5)
    lstCds.Items.Add(strConcatenatedInfo)
End If

Acamar Monday, November 30, 2009 12:45 AM

You can use google to search for other answers

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