#include<iostream>
using namespace std;
class Circle
{
private:  
    float r;
    float f;
    float l;
public:
    void outf();
    void outl();
};
void Circle::outf(void)
{
    f=2*3.14*r;
    cout<<"f is:"<<f<<endl;
}
void Circle::outl(void)
{
    l=3.14*r*r;
    cout<<"l is:"<<l<<endl;
}
void main()
{
    double f,l,r;
    Circle c;
    cin>>r;
    c.outf();
    c.outl();
}哪里有错误啊，帮忙改下，谢谢了