Simple Function to write in Text File for error log

First of all you have to import name space

Imports System.IO

then you can write this simple function

Dim FilePath As String = Application.StartupPath + "\Error.log"
Public Sub WriteLog(ByVal StrError As String)
Try
If File.Exists(FilePath) Then
Using Writer As New System.IO.StreamWriter(FilePath, True)
Writer.WriteLine(Now() + "  |  " + StrError)
End Using
Else
Dim fs As FileStream = Nothing
fs = File.Create(FilePath)
Using fs
End Using
Using Writer As New System.IO.StreamWriter(FilePath, True)
Writer.WriteLine(Now() + "  |  " + StrError)
End Using
End If
Catch ex As Exception
End Try
End Sub

Dos Print from Datagridview in VB.Net

Private Sub DosPrint()
        Try

            Dim table As New DataTable
            Dim i As Integer
            Dim j As Integer
            Dim Collist(dgvreport.ColumnCount) As String
            Dim TotalLen As Integer = 0
            Dim LineCount As Integer = 0
            Dim PageCount As Integer = 1
            Dim StrSeprator As String = ""



            ''========== Check total len from Each Rows ===============
            For Each dc As DataGridViewColumn In dgvreport.Columns
                If dc.Visible = True Then
                    Dim temp As Integer = dc.HeaderText.Length
                    For Each dr As DataGridViewRow In dgvreport.Rows
                        Dim drlen As Integer = dr.Cells(dc.Name).Value.ToString.Length
                        If temp < drlen Then
                            temp = drlen
                        End If
                    Next
                    Collist(dc.Index) = temp
                    TotalLen = TotalLen + temp
                End If

            Next

            Using Writer As New System.IO.StreamWriter("C:\Testfile.txt")

                ''=================== Write Reprot Header ================
                Writer.WriteLine("")
                Writer.WriteLine(Space(20) + Chr(27) + Chr(71) + Chr(14) + _
                                    Chr(27) + Chr(45) + Chr(1) + "Company Name" + _
                                    Chr(27) + Chr(72) + Chr(20) + _
                                    Chr(27) + Chr(45) + Chr(0))     '' For Bold and Enlarge
                Writer.WriteLine(lblHeader.Text)
                Writer.WriteLine("")

                For k As Integer = 0 To TotalLen

                    Writer.Write("=")

                Next

                Dim strCOl As String = ""
                Dim strRow As String = ""

                ''============= Write Col Header for First Page ======================================
                Dim iC As Integer = 1
                Dim iR As Integer = 1
                For j = 0 To dgvreport.ColumnCount - 1
                    If dgvreport.Columns(j).Visible = True Then
                        strCOl = strCOl + "  " + dgvreport.Columns(j).HeaderText.ToString() + Space(CInt(Collist(j)) - CInt(dgvreport.Columns(j).HeaderText.Length))

                        iC = iC + 1
                    End If
                Next

                Writer.WriteLine("")
                Writer.WriteLine(Chr(27) + Chr(27) + strCOl + Chr(27) + Chr(72))

                For k As Integer = 0 To TotalLen
                    StrSeprator = StrSeprator + "="
                Next

                Writer.WriteLine(StrSeprator)
                Writer.WriteLine("")

                ''======== End First Col ========================




                For i = 0 To dgvreport.RowCount - 1

                    If LineCount >= 60 Then  '' Check Lines per page
                        LineCount = 0
                        '' Ending First Page
                        Writer.WriteLine(StrSeprator)
                        Writer.WriteLine("Page: " + PageCount.ToString) ''Write Page Number
                        PageCount = PageCount + 1
                        Writer.WriteLine("")
                        Writer.Write(Chr(13)) '' Line Break


                        ''============= Write Col Header for Other Page ======================================
                        Writer.WriteLine("")
                        Writer.WriteLine(StrSeprator)
                        Writer.WriteLine(Chr(27) + Chr(27) + strCOl + Chr(27) + Chr(72))
                        Writer.WriteLine(StrSeprator)
                        Writer.WriteLine("")

                        ''======== End Other Col header ========================


                    End If

                    If dgvreport.Rows(i).Visible = True Then
                        iR = iR + 1
                        iC = 1
                        For j = 0 To dgvreport.ColumnCount - 1
                            If dgvreport.Columns(j).Visible = True Then
                                strRow = strRow + "  " + dgvreport(j, i).Value.ToString() + Space(CInt(Collist(j)) - CInt(dgvreport(j, i).Value.ToString.Length))
                                iC = iC + 1
                            End If
                        Next
                    End If


                    Writer.WriteLine(strRow)
                    strRow = ""
                    LineCount = LineCount + 1

                Next



                Writer.WriteLine(StrSeprator)
                Writer.Close()

            End Using



        Catch ex As Exception
            MsgBox(ex.Message.ToString)
        End Try
    End Sub