private void button1_Click(object sender, EventArgs e)
{
double c = Convert.ToDouble(textBox1.Text.Trim());
double k = Convert.ToDouble(textBox2.Text.Trim());
Rectangular R = new Rectangular(c, k);
label3.Text = "矩形面积:" + R.GetArea();
}
private void button1_Click(object sender, EventArgs e)
{
if (textBox1.Text == string.Empty || textBox2.Text == string.Empty)
{
errorProvider1.SetError(textBox1, "矩形边长不能为空值！");
return;
}
double c = Convert.ToDouble(textBox1.Text.Trim());
double k = Convert.ToDouble(textBox2.Text.Trim());
Rectangular R = new Rectangular(c, k);
label3.Text = "矩形面积:" + R.GetArea();
}