private void AddUserBtn_Click(object sender, EventArgs e) { if (!FormValidator.FirstNameValidation(FirstNameBox.Text)) { string invalidMessage = "Invalid first name.\nValid first name contains:" + "\n-letters only\n-one uppercase letter at the beginnig" + "\n-at least one lowercase letter\n-max 25 letters"; errorProvider1.SetError(FirstNameBox, invalidMessage); return; } if (!FormValidator.LastNameValidation(LastNameBox.Text)) { string invalidMessage = "Invalid last name.\nValid last name contains:" + "\n-letters only\n-one uppercase letter at the beginnig\n-max 25 letters"; errorProvider1.SetError(LastNameBox, invalidMessage); return; } errorProvider1.Clear(); _dataBase.AddUser(FirstNameBox.Text, LastNameBox.Text); FirstNameBox.Clear(); LastNameBox.Clear(); UpdateUsersBox(); }