haveSearchedTimes = 0;
                string path = System.Environment.CurrentDirectory;
                DirectoryInfo di = new DirectoryInfo(path);
                foreach (var sdi in di.GetDirectories())
                {
                    foreach (var fi in sdi.GetFiles("*.txt"))
                    {
                        var result = Search(fi);
                        if (!string.IsNullOrEmpty(result))
                        {
                            richTextBox1.Clear();
                            //richTextBox1.SelectionBackColor = Color.White;
                            //richTextBox1.Select(0, 0);
                            richTextBox1.Text = result;
                            int start = -pattern.Length;
                            for (int i = 0; i < matchTimes; i++)
                            {
                                start = richTextBox1.Find(pattern, start + pattern.Length, RichTextBoxFinds.NoHighlight);
                            }
                            richTextBox1.Select(start, pattern.Length);
                            richTextBox1.SelectionBackColor = Color.Red;
                            return;
                        }
                    }
                }