cir.h
#ifndef CIR_H
#define CIR_H
namespace cir{
double PI=3.1415926;
double getPerimeter(double radis){
return 2*PI*radis;
};
double getArea(double radis){
return PI*radis*radis;
};
}
#endif // CIR_H
main.cpp
#include <iostream>
#include "cir.h"
using namespace std;
using namespace cir;
int main()
{
cout << "面积:" << getArea(5) << endl;
cout << getPerimeter(5) << endl;
return 0;
}