Public Class Form1
 
    Private dt As New DataTable
 
    Private Sub maketable()
        Dim dc0 As New DataColumn("ID", GetType(Integer))
        dc0.AutoIncrement = True
        dt.Columns.Add(dc0)
        Dim dc1 As New DataColumn("Name", GetType(String))
        dt.Columns.Add(dc1)
        Dim dc2 As New DataColumn("Item", GetType(String))
        dt.Columns.Add(dc2)
        Dim dc3 As New DataColumn("CompanyName", GetType(String))
        dt.Columns.Add(dc3)
        For i As Integer = 0 To 5
            Dim dr As DataRow = dt.NewRow
            dr(1) = "Name" & i.ToString
            dr(2) = "Item" & i.ToString
            dr(3) = "Company" & i.ToString
            dt.Rows.Add(dr)
        Next
        dt.AcceptChanges()
    End Sub
 
    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        maketable() ' get some dummy data
        DataGridView1.DataSource = dt
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        'get the value from the current row
        Dim dgvr As DataGridViewRow = DataGridView1.CurrentRow
        If Not dgvr Is Nothing Then
            Label1.Text = dgvr.Cells("CompanyName").Value
        End If
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        'get the value from the row specified in the textbox
        If Not IsNumeric(TextBox1.Text) Then Exit Sub
        Dim rowindex As Integer = CInt(TextBox1.Text)
        If rowindex > DataGridView1.RowCount Then Exit Sub
        Dim dgvr As DataGridViewRow = DataGridView1.Rows(rowindex)
        If Not dgvr Is Nothing Then
            Label2.Text = dgvr.Cells("CompanyName").Value
        End If
    End Sub
 
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        'get the values from all rows
        Dim labeltext As String = ""
        For Each dgvr As DataGridViewRow In DataGridView1.Rows
            labeltext &= dgvr.Cells("CompanyName").Value & vbCrLf
        Next
        Label3.Text = labeltext
    End Sub
End Class

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