private void buttonsignin_Click(object sender, RoutedEventArgs e) { List <string> Signin = new List <string>(); using (StreamReader sr = new StreamReader("register.txt")) { Signin.Add(sr.ReadLine()); } int k = 0; for (int i = 0; i < Signin.Count; i++) { string[] loginpassword = Signin[i].Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries); if (loginpassword[0] == textBoxlogin.Text && loginpassword[1] == passwordBox.Password) { k = 1; Profile _profile = new Profile(); SignInWindow.Close(); _profile.ShowDialog(); } } if (k == 0) { MessageBox.Show("Пользователя с таким логином и паролем не существует.", "Ошибка", MessageBoxButton.OK, MessageBoxImage.Error); } }