Qncho - 1 Zad.

// FORM 1
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;
using static System.Windows.Forms.VisualStyles.VisualStyleElement;

namespace test2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {

            textBox1.Text = ("New User");

        }
private void textBox2_TextChanged(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {
            listBox1.Items.Add(textBox1.Text);
            listBox1.Items.Add(textBox2.Text);
            listBox1.Items.Add(textBox3.Text);
            listBox1.Items.Add(comboBox1.Text);
            listBox1.Items.Add(comboBox2.Text);

        }

        private void button3_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
        }

        private void button4_Click(object sender, EventArgs e)
        {

            double litre;
            int n;
            double ostupka;
            double sum;
            litre = Convert.ToDouble(textBox2.Text);
            n = Convert.ToInt32(textBox3.Text);
            ostupka = Convert.ToDouble(comboBox2.Text);
            sum= (litre*n- ((litre * n )* (ostupka / 100)))*1.2;
            textBox4.Text = sum.ToString();
            Form2 f = new Form2(textBox1.Text, textBox2.Text,textBox3.Text, comboBox1.Text, comboBox2.Text);
            f.Show();
        }
    }
}

// FORM 2
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace test2
{
    public partial class Form2 : Form
    {
        String a;

        public Form2(string b,string c,string d,string f,string a)
        {
            InitializeComponent();
            this.a = a+b+c+d+f;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            StreamWriter s=new StreamWriter(@"File.txt");
            s.Write(a);
                s.Close();
        }
    }
}