C# Windows Application Form

code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace PersonalInformationApp
{
    public partial class MainUI : Form
    {
        public MainUI()
        {
            InitializeComponent();
        }

        private string firstName, lastName, fathersName, mothersName, address;

        private void AddressButton_click(object sender, EventArgs e)
        {
            MessageBox.Show(address);

        }

        private void parentsButton_click(object sender, EventArgs e)
        {
            fathersNameTextBox.Text = fathersName;
            mothersNameTextBox.Text = mothersName;
            MessageBox.Show("Fathers Name: " + fathersName + "\n" + "Mothers Name: " + mothersName);
        }

        private void saveButton_Click(object sender, EventArgs e)
        {
            firstName = firstNameTextBox.Text;
            lastName = lastNameTextBox.Text;
            fathersName = fathersNameTextBox.Text;
            mothersName = mothersNameTextBox.Text;
            address = addressTextBox.Text;

            firstNameTextBox.Text = "";
            lastNameTextBox.Clear();
            fathersNameTextBox.Text=string.Empty;
            mothersNameTextBox.Text = string.Empty;
            addressTextBox.Text = null;
        }

        private void showAllInformationButton_Click(object sender, EventArgs e)
        {
            firstNameTextBox.Text = firstName;
            lastNameTextBox.Text = lastName;
            fathersNameTextBox.Text = fathersName;
            mothersNameTextBox.Text = mothersName;
            addressTextBox.Text = address;
        }

        private void nameButton_Click(object sender, EventArgs e)
        {
            MessageBox.Show(firstName+" "+lastName);
        }

      
    }
}