..................Desigining code for two Radio button.............
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.............cs code for button click.............................
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protected void Button1_Click(object sender, EventArgs e)
    {
        if (RadioButton1.Checked)
        {

            TextBox1.Text = RadioButton1.Text.ToString();
        }
        else if (RadioButton2.Checked)
        {
            TextBox1.Text = RadioButton2.Text.ToString();
        }
        else
        {
            TextBox1.Text = "select any one";        
        
        }
    }
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