CurrencyConverterWindowsForm

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

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

        public void textBox1_TextChanged(object sender, EventArgs e)
        {
        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            double currencyEntered = double.Parse(textBox1.Text);

            string selectedCurrency = comboBox1.SelectedItem.ToString();

            switch (selectedCurrency)
            {
                case "BGN":
                    {
                        textBox2.Text = currencyEntered.ToString();
                        textBox3.Text = (Math.Round((currencyEntered / 1.95), 2)).ToString();
                        textBox4.Text = (Math.Round((currencyEntered / 1.45), 2)).ToString();
                        textBox5.Text = (Math.Round((currencyEntered / 2.45), 2)).ToString();
                        break;
                    }
                case "EUR":
                    {
                        textBox3.Text = currencyEntered.ToString();
                        textBox2.Text = (currencyEntered * 1.95).ToString();
                        textBox4.Text = (currencyEntered * 0.45).ToString();
                        textBox5.Text = (currencyEntered * 1.20).ToString();
                        break;
                    }
                case "USD":
                    {
                        textBox4.Text = currencyEntered.ToString();
                        textBox2.Text = (currencyEntered / 0.45).ToString();
                        textBox3.Text = (currencyEntered / 1.45).ToString();
                        textBox5.Text = (currencyEntered / 0.85).ToString();
                        break;
                    }
                case "GBP":
                    {
                        textBox5.Text = currencyEntered.ToString();
                        textBox2.Text = (currencyEntered / 1.2).ToString();
                        textBox3.Text = (currencyEntered * 0.85).ToString();
                        textBox4.Text = (currencyEntered * 2.45).ToString();
                        break;
                    }
            }
        }
    }
}