#include "stdafx.h"
#include <iostream>
using namespace std;


int main(int argc, char* argv[])
{
    double a, b, c, d, r, area;     // 變數宣告
	double pi = 3.1415926;
	int choice;
    char status = 'y';    // status = 'y'
  
    while(status == 'y')    
    {
	cout << "請選擇計算功能1.三角形面積 2.長方形面積 3.圓面積 : ";
    cin >> choice;
     switch(choice)
	 {
      case 1: cout << endl << "請輸入三角形底及高 : " ;
              cin >> a >> b;
			  area = a * b / 2;
              cout << endl << "三角形面積 : " << area << "平方單位" << endl ;
              break;
      case 2: cout << endl << "請輸入長方形長及寬 : ";
		      cin >> c >> d;
			  area = c * d;
              cout << endl << "長方形面積 : " << area << "平方單位" << endl ;
              break;
      case 3: cout << endl << "請輸入圓形半徑 : ";
		      cin >> r;
			  area = r * r * pi;
              cout << endl << "圓形面積 : " << area << "平方單位" << endl ;
              break;
      default: cout << endl <<"輸入數值錯誤 !!!"
                    << endl;	
	 }
      cout << "是否要繼續計算(按 n 跳出）";
       cin >> status;
    }
return 0;
}