Private Declare Ansi Function GetPrivateProfileString Lib "kernel32.dll" Alias _
   "GetPrivateProfileStringA" (ByVal lpApplicationName As String, ByVal _
   lpKeyName As String, ByVal lpDefault As String, ByVal lpReturnedString As _
   String, ByVal nSize As Int32, ByVal lpFileName As String) As Int32
    Private Declare Ansi Function WritePrivateProfileString Lib "kernel32.dll" _
    Alias "WritePrivateProfileStringA" (ByVal lpApplicationName As String, _
    ByVal lpKeyName As String, ByVal lpString As String, ByVal lpFileName As _
    String) As Int32
        Dim myIniFile As String
        Dim sValue As String
        Dim lResult As Object
        Dim Meldung As String
        myIniFile = " C:\Test\Test.ini" 'durchsuchen der .ini
        Meldung = "Soll die Test.ini automatisch angepasst werden?"
        sValue = Space$(255)
        lResult = GetPrivateProfileString("Test", _
          "", sValue, Len(sValue), myIniFile) = 0 'wenn Eintrag nicht 
          ' gefunden-> MsgBox
        MsgBox(Meldung, MessageBoxButtons.YesNo, "Test.ini ist nicht" & _
          "konfiguriert!")

Option Strict On
Option Explicit On
 
Public Class frmIni
 
   <System.Runtime.InteropServices.DllImport("kernel32.dll", _
     SetLastError:=True)> _
   Private Shared Function GetPrivateProfileString _
                       (ByVal lpAppName As String, _
                        ByVal lpKeyName As String, _
                        ByVal lpDefault As String, _
                        ByVal lpReturnedString As System.Text.StringBuilder, _
                        ByVal nSize As Integer, _
                        ByVal lpFileName As String) As Integer
    End Function
 
 
    Private Sub frmIni_Load(sender As System.Object, _
        e As System.EventArgs) Handles MyBase.Load
 
        Dim myIniFile As String
        Dim lResult As Int32
        Dim Meldung As String = "Ini-Konfiguration"
 
        myIniFile = "C:\Daten\Test.ini"
 
        If Not IO.File.Exists(myIniFile) Then
            MsgBox("Ini nicht gefunden", , Meldung)
        Else
            Dim sValue As New System.Text.StringBuilder(500)
 
            lResult = GetPrivateProfileString _
                ("MeineSektion", "MeinSchluessel", "", sValue, sValue.Capacity, _
                  myIniFile)
 
            If lResult = 0 Then
                If MsgBox("Test.ini ist nicht konfiguriert!", _
                MsgBoxStyle.YesNo, Meldung) = MsgBoxResult.Yes Then
                    '.......
                End If
            Else
                MsgBox("Schlüsselwert: " & sValue.ToString, , Meldung)
            End If
        End If
    End Sub
End Class

Option Strict On
Option Explicit On
 
Public Class frmIni
 
    <System.Runtime.InteropServices.DllImport("kernel32.dll", _
      SetLastError:=True)> _
    Private Shared Function GetPrivateProfileString(ByVal lpAppName As String, _
                            ByVal lpKeyName As String, _
                            ByVal lpDefault As String, _
                            ByVal lpReturnedString As _
                            System.Text.StringBuilder, _
                            ByVal nSize As Integer, _
                            ByVal lpFileName As String) As Integer
    End Function
 
 
    <System.Runtime.InteropServices.DllImport _
        ("kernel32.dll", SetLastError:=True)> _
    Private Shared Function WritePrivateProfileString(ByVal lpAppName As _
    String, _
                        ByVal lpKeyName As String, _
                        ByVal lpString As String, _
                        ByVal lpFileName As String) As Boolean
    End Function
 
 
    Private Sub frm_Load(sender As System.Object, _
        e As System.EventArgs) Handles MyBase.Load
 
        Dim myIniFile As String
        Dim Meldung As String = "Ini-Konfiguration"
 
        myIniFile = "C:\Daten\Test.ini"
 
        If Not IO.File.Exists(myIniFile) Then
            MsgBox("Ini nicht gefunden", , Meldung)
        Else
            If ContainsSection(myIniFile, "Test") Then
                Process.Start("Notepad.exe")
            Else
                If MsgBox("Sektion Test nicht in der Ini gefunden." & vbCrLf & _
                    "Soll die Section und der Key ergänzt werden? ", _
                    MsgBoxStyle.YesNo, Meldung) = MsgBoxResult.Yes Then
 
                    WritePrivateProfileString("Test", "Test", "1", myIniFile)
                Else
                    Process.Start("Notepad.exe")
                End If
            End If
        End If
    End Sub
 
 
    Private Function ContainsSection(IniFile As String, _
           Section As String) As Boolean
 
        Section = Section.TrimStart("["c)
        Section = Section.TrimEnd("]"c)
 
        Dim lines() As String = IO.File.ReadAllLines(IniFile)
        For i As Integer = 0 To lines.Count - 1
            If lines(i).Trim.StartsWith("[") AndAlso _
               lines(i).Trim.EndsWith("]") Then
 
                If lines(i).ToLower = "[" & Section.ToLower & "]" Then
                    Return True : Exit Function
                End If
            End If
        Next i
        Return False
    End Function
 
End Class