求解释行C++

#include <iostream>
#include <iomanip>
using namespace std;
class Point
{
    public:
    Point(double aa=0,double bb=0)
    {
        x=aa;
        y=bb;
    }
    void show()
    {
        cout<<"Point : ("<<setprecision(16)<<x<<", "<<y<<")\n";
    }
    private:
    double x,y;
};
int main()
{
    char c;
    double a, b;
    Point q;
    while(std::cin>>a>>c>>b)
    {
        Point p(a, b);
        p.show();
    }
    q.show();
}

Point p;
Point.Point (a,b);