C++:菜鸟，这段代码有错，哪位高手能解释上出错的原因

C++:初学者，这段代码有错，谁能解释下出错的原因

C/C++ code

#include <iostream>using namespace std;class Circle{public:    Circle(double radius = 0){        Pi =3.14;        this->radius = radius;    }     double getArea(){        return Pi* radius* radius;    }    double getCircumference(){        return 2*Pi* radius;    }private:    const double Pi ;    double radius ;    };  int main(int argc, char *argv[]){    cout << "Enter a radius: ";double Radius = 0;cin >> Radius;Circle MyCircle(Radius);cout << "Circumference = " << MyCircle.getCircumference() << endl;cout << "Area = " << MyCircle.getArea() << endl;    return 0;}

C/C++ code

class Circle{public:    Circle(double radius = 0):Pi(3.14){        //Pi =3.14;        this->radius = radius;    }     double getArea(){        return Pi* radius* radius;    }    double getCircumference(){        return 2*Pi* radius;    }private:    const double Pi ;    double radius ;};