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

        private void button1_Click(object sender, EventArgs e)
        {
            double r;
            r = double.Parse(txtR.Text);
            MyCircle aCircle = new MyCircle(r);


            double aArea = aCircle.CircleArea();
            dblArea.Text = aArea.ToString("f4");
        }

        private void txtR_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
                MessageBox.Show("您在textBox1里按下了回车键");

                double r;
                r = double.Parse(txtR.Text);
                MyCircle aCircle = new MyCircle(r);


                double aArea = aCircle.CircleArea();
                dblArea.Text = aArea.ToString("f4");
            }
        }
    }
}