C#

private void btnUpDown_Click(object sender, RoutedEventArgs e)
{
    Button btn = (Button)sender;
    switch (btn.Name)
    {
        case "btnUp" : etage++; break;
        case "btnDown" : etage--; break;
    }
    lblHuidigeVerdieping.Content = etage.ToString();
}

void WijzigVerdieping(bool omhoog) {
     if (omhoog) etage++; else etage--;
     lblHuidigeVerdieping.Content = etage.ToString();
 }

 private void btnUp_Click(object sender, RoutedEventArgs e) {
     WijzigVerdieping(true);
 }

 private void btnDown_Click(object sender, RoutedEventArgs e) {
     WijzigVerdieping(false);
 }

// note: I have not tested this code ... I don't use WPF; but, I am confident this is valid. 

namespace Whatever
{
    public enum Verdieping
    {
        kelder = -1,  // you could omit this
        gelijksvloers,
        een,
        twee,
        drie
    }

    public partial class MainWindow : Window
    { 
        private int tally;

        public MainWindow()
        {
            InitializeComponent();

            lblHuidigeVerdieping.Text = Verdieping.gelijksvloers.ToString()};

            tally = 0;
        }

        private void TallyButtons_Click(object sender, RoutedEventArgs  e)
        {
            if (sender.Equals(btnDown))
            {
                if (tally == (int)Verdieping.gelijksvloers)
                {
                    // throw an error ?
                    // show a dialog ?
    
                    return;
                }
    
                tally--;
            }
            else
            {
                if (tally == (int) Verdieping.drie)
                {
                    // throw an error ?
                    // show a dialog ?
    
                    return;
                }
    
                tally++;
            }

            lblHuidigeVerdieping.Text = tally.ToString();
        }
    }
}

static void ReadMail(){
    Microsoft.Office.Interop.Outlook.Application app = null;
    Microsoft.Office.Interop.Outlook._NameSpace ns = null;
    Microsoft.Office.Interop.Outlook.MAPIFolder inboxFolder = null;
    app = new Microsoft.Office.Interop.Outlook.Application();
    ns = app.GetNamespace("MAPI");
    inboxFolder = ns.GetDefaultFolder(Microsoft.Office.Interop.Outlook.OlDefaultFolders.olFolderInbox);
    Outlook.Items Items = inboxFolder.Items.Restrict("[LastModificationTime] > '01/1/2003'");

    foreach (var item in Items){
        var mail = (Outlook.MailItem)item;
        mail.Body = mail.Body.Replace("Text to be replaced", "Replacing text");
        mail.Save();
    }

}

int port = 2195;
            String hostname = "gateway.push.apple.com";

try
           {
               TcpClient client = new TcpClient(hostname, port);
               SslStream sslStream = new SslStream(client.GetStream(), false, new RemoteCertificateValidationCallback(ValidateServerCertificate), null);

               try
               {
                   sslStream.AuthenticateAsClient(hostname, certificatesCollection, System.Security.Authentication.SslProtocols.Tls, false);

                   for (int i = 0; i < Token.Length; i++)
                   {
                       HttpContext.Current.Trace.Warn("inside sendPushNotificationApple, dt=" + Token[i]);
                       MemoryStream memoryStream = new MemoryStream();
                       BinaryWriter writer = new BinaryWriter(memoryStream);
                       writer.Write((byte)0);
                       writer.Write((byte)0);
                       writer.Write((byte)32);

                       writer.Write(HexStringToByteArray(Token[i]));
                       String payload = "{ \"aps\" : { \"alert\" : {\"title\" : \"" + szAppName + "\",\"body\" : \"" + message + "\",\"Type\" : \"" + szType + "\"} }}";
                       HttpContext.Current.Trace.Warn("inside sendPushNotificationApple, payload=" + payload.ToString());
                       writer.Write((byte)0);
                       //writer.Write((byte)payload.Length);
                       byte[] b1 = System.Text.Encoding.UTF8.GetBytes(payload);
                       writer.Write((byte)b1.Length);
                       writer.Write(b1);
                       writer.Flush();
                       byte[] array = memoryStream.ToArray();
                       sslStream.Write(array);
                       sslStream.Flush();
                   }

                   client.Close();
               }
               catch (System.Security.Authentication.AuthenticationException ex)
               {
                   HttpContext.Current.Trace.Warn("inside sendPushNotificationApple, AuthenticationException=" + ex.ToString());
                   client.Close();
               }
               catch (Exception exp)
               {
                   HttpContext.Current.Trace.Warn("inside sendPushNotificationApple, Exception=" + exp.ToString());
                   client.Close();
               }
           }
           catch (Exception ex)
           {
               HttpContext.Current.Trace.Warn("inside sendPushNotificationApple, Exception1=" + ex.ToString());
           }