// C2_6.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>

using namespace std;

int main(int argc, char* argv[])
{
   double r = 0.0 ;              // 設定初始值
   const double pi =3.1416;          
   const double area = 0.0;     

   cout << endl                           
        << "請輸入半徑值 \? ";
   cin >> r;

   cout << endl							
         << "圓面積 : ";
   cout << pi * r * r ;
   cout << endl;                           
   return 0;
}