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

        private void Conversion_Click(object sender, EventArgs e)
        {
            if ((!checkBox1.Checked) && (!checkBox2.Checked) && (!checkBox3.Checked))
            {
                textBox2.Text = textBox1.Text;
            }
            else
            {
                foreach (char ch in textBox1.Text)
                {
                    string temp = ch.ToString();
                    if (checkBox1.Checked)
                    {
                        if (char.IsDigit(ch))
                            temp = "";
                    }
                    if (checkBox2.Checked)
                    {
                        if (char.IsLower(ch))
                            temp = (char.ToUpper(ch).ToString());
                        else if(char.IsUpper(ch))
                            temp = (char.ToLower(ch).ToString());
                    }
                    if (checkBox3.Checked)
                    {
                        if (char.IsWhiteSpace(ch))
                            temp = "";
                    }
                    textBox2.Text += temp;
                }
            }

        }
    }
}