.......Desining code for cheackbox 1,2,3...........................
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.................designing code for button..........................
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....................Designing code for Textbox.....................
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......................CS code for button click.....................
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 protected void Button1_Click(object sender, EventArgs e)
    {

        {
            string s = "";

            if (CheckBox1.Checked)
            {
                s =s+ CheckBox1.Text.ToString()+"\n";
            
            }
            if (CheckBox2.Checked)
            {
                s = s + CheckBox2.Text.ToString() + "\n";

            }
            if (CheckBox3.Checked)
            {
                s = s + CheckBox3.Text.ToString() +;

            }
            TextBox1.Text = s;
        }

    }
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