3_11.cpp

10个比较经典的C++程序。初学者就先多学习学习别人吧。

#include <iostream> 
using namespace std;
void ComCircle(double&, double&, double); //函数的原型声明
int main()
{ double r, a, c;
  cout << "Enter radius: ";  cin >> r;
  ComCircle(a, c, r);
  cout << "The area = " << a << ", and the circumference = " << c << endl;
  return 0;
}
void ComCircle(double& area, double& circum, double r) //通过引用变量返回面积和周长
{ const double PI = 3.141592653589793;
  area = PI*r*r;  circum = 2*PI*r;				//计算面积和周长
}