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 demo4
{
    public partial class Form1 : Form
    {
        public Form1()
        {            InitializeComponent();        }
        private void button1_Click(object sender, EventArgs e)
        {
            CGraph C = new CGraph();        				//实例化CGraph
            if (textBox1.Text.Trim() != "") 					//判断textBox1是否有输入
            {
                if (textBox1.Text.Trim().IndexOf('.') == 1)			//所输入中不包含“.”
                {
                    int i1 = Convert.ToInt32(textBox1.Text.Trim());	//转换为int类型
                    C.calculate(i1);        				//调用calculate方法计算面积
                }
                else  							//所输入中包含“.”，则转换为double类型
                {
                    double d1 = Convert.ToDouble(textBox1.Text.Trim());
                    C.calculate(d1);
                }
            }
            else if (textBox2.Text.Trim() != "" && textBox3.Text.Trim() != "")
            {
                double d2 = Convert.ToDouble(textBox2.Text.Trim());
                double d3 = Convert.ToDouble(textBox3.Text.Trim());
                C.calculate(d2, d3);
            }
            else if (textBox4.Text.Trim() != "" && textBox5.Text.Trim() != "" && textBox6.Text.Trim() != "")
            {
                double d4 = Convert.ToDouble(textBox4.Text.Trim());
                double d5 = Convert.ToDouble(textBox5.Text.Trim());
                double d6 = Convert.ToDouble(textBox6.Text.Trim());
                C.calculate(d4, d5, d6);
            }
            label7.Text = CGraph.result;
        }
        private void button2_Click_1(object sender, EventArgs e)
        {
            textBox1.Text = textBox2.Text = textBox3.Text = textBox4.Text = textBox5.Text = textBox6.Text = "";
            label7.Text = string.Empty;
        }
    }
    class CGraph
    {
        double S;               							//面积
        public static string result = "没有结果";					//最终输出的结果
        public void calculate(double r)  						//计算高精度圆面积
        {

            S = Math.PI * r * r;
            result = "高精度圆面积为：" + S.ToString();
        }
        public void calculate(int r)							//计算低精度圆面积
        {
            S = 3.1416 * r * r;
            result = "低精度圆面积为：" + S.ToString();
        }
        public void calculate(double c, double k)  				//计算矩形面积
        {
            S = c * k;
            result = "计算矩形面积:" + S.ToString();
        }
        public void calculate(double a1, double a2, double a3)		//计算三角形面积
        {
            //利用海伦公式求三角形面积
            double P = 0.5 * (a1 + a2 + a3);
            S = Math.Sqrt(P * (P - a1) * (P - a2) * (P - a3));
            result = "三角形面积:" + S.ToString();

        }
    }
}