private void button1_Click(object sender, EventArgs e)
{
rec a = new rec(Convert.ToInt32(textBox1.Text), Convert.ToInt32(textBox2.Text));
ar = a.getarea();
label4.Text = "Area is :" + ar;
}
private void button2_Click(object sender, EventArgs e)
{
rec a = new rec(Convert.ToInt32(textBox1.Text), Convert.ToInt32(textBox2.Text));
ar = a.getarea();
int cost = a.getcost(ar);
label3.Text += "\n Cost is: " + cost;
}