recursion c#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.IO;

namespace WpfApplication2
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            string sourcePath = @"C:\temp\";

            static void DirSearch(string sourcePath)
            {
                try
                {
                    foreach (string d in Directory.GetDirectories(sourcePath))
                    {
                        foreach (string f in Directory.GetFiles(d))
                        {
                            listBox1.Items.Add(f);
                        }
                        DirSearch(d);
                    }
                }
                catch (Exception ex)
                {
                    listBox1.Items.Add(ex.Message);
                }
            }
        }



    }
}