代碼文本：
//#include "stdafx.h"//vc++ 6.0? Maybe should add this line.
#include <iostream>
using namespace std;
int main(int argc,char *argv[]){
double r,pai=3.1415926;
int k;
cout << "Enter r & k(r>0 & k>0(1,2,3)...\n";
if((cin >> r >> k) && r>0 && (k==1 || k==2 || k==3)){
switch(k){
case 1:
cout << "S = " << pai*r*r << endl;
break;
case 2:
cout << "L = " << pai*(r+r) << endl;
break;
case 3:
cout << "S = " << pai*r*r << endl << "L = " << pai*(r+r) << endl;
break;
}
}
else
cout << "Input error, exit...\n";
return 0;
}