private void inputTextBox_KeyDown(object sender, KeyEventArgs e)
        {
            // if user pressed enter key
            if (e.KeyCode == Keys.Enter)
            {
                // create a filename to write to file
                string fileName = inputTextBox_KeyDown.Text;

                // determine whether fileName is a file
                if (FileDialog.Exists(fileName))
                {
                    // get files creation date, modification date etc
                    GetInformation(fileName);
                    StreamReader stream = null; // declare StreamReader
                    try
                    {
                        // obtain reader and file contents
                        using (stream = new StreamReader(fileName))
                        {
                            outputTextBox.AppendText(stream.ReadToEnd());
                        }// end using
                    }// end try
                    catch (IOException)
                    {
                        MessageBox.Show("Error reading from file", "File Error", MessageBoxButtons.OK, MessageBoxIcon.Error);

                    }// end catch
                }// end if
                // determine whether fileName is a directory
                else if (Directory.Exists(fileName))
                {
                    // get directory's creations date,
                    // modification date, etc
                    GetInformation(fileName);


                    //obtain directory list of specified directory
                    string[] directoryList = Directory.GetDirectories(fileName);

                    outputTextBox.AppendText("Directory contents:\n");

                    // output directoryList contents
                    foreach (var directory in directoryList)
                        outputTextBox.AppendText("Directory contents:\n");
                } // end else if
                else
                {
                    // notify user that neither file nor directory exists
                    MessageBox.Show(inputTextBox_KeyDown.Text + " does not exist", "File Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }// end else
            }// end if
        }// end method inputTextBox_KeyDown