Public Class Form1
    Declare Function WritePrivateProfileString Lib "kernel32" Alias _
      "WritePrivateProfileStringA" (ByVal lpApplicationName As String, ByVal _
      lpKeyName As Char, ByVal lpString As Char, ByVal lpFileName As String) As _
      Long
    Declare Function GetPrivateProfileString Lib "kernel32" Alias _
    "GetPrivateProfileStringA" (ByVal lpApplicationName As String, ByVal _
    lpKeyName As Char, ByVal lpDefault As String, ByVal lpReturnesString As _
    String, ByVal nSize As Long, ByVal lpFileName As String) As Long
    Declare Function GetPrivateProfileInt Lib "kernel32" Alias _
    "GetPrivateProfileIntA" (ByVal lpApplication As String, ByVal lpKeyName As _
    String, ByVal dDefault As Long, ByVal lpFileName As String) As Long
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Dim Wert1 As Double
        Dim Wert2 As Double
        Dim Wert3 As Double
 
 
        Wert1 = Convert.ToDouble(TextBox1.Text.Replace(".", ","))
        Wert2 = Convert.ToDouble(TextBox2.Text.Replace(".", ","))
        Wert3 = Convert.ToDouble(TextBox3.Text.Replace(".", ","))
 
        WritePrivateProfileString("Test1", "Wert1", Wert1, _
          My.application.info.DirectoryPath & "\test1.ini")
 
 
 
    End Sub
End Class