C++类模板静态成员处理

#include<iostream>
using namespace std;
const double PI=3.14159;
template<typename T>
class Circle{
    T radius;
    static int total;
public:
    Circle(T r=0){
        radius=r;
        total++;
    }
    void SetRadius(T r){
        radius=r;
    }
    T GetRadius()const{
        return radius;
    }
    double GetArea()const{
        return PI*radius*radius;
    }
    static int ShowTotal();
};

template<typename T>
int Circle<T>::total=0;

template<typename T>
int Circle<T>::ShowTotal(){
    return total;
}
int main(){
    Circle<int>A,B;
    A.SetRadius(10);
    cout<<A.GetArea()<<endl;
    B.SetRadius(100);
    cout<<B.GetArea()<<endl;
    cout<<Circle<int>::ShowTotal()<<endl;

    return 0;
}