为什么显示（“pl”: 未声明的标识符）（小白，求解答）

Question

#include
#include
using namespace std;
class Point
{
public:
Point(double xi =0,double yi=0)
{x=xi;y=yi;}
double GetX(){return x;}
double GetY(){return y;}
private:
double x;
double y;
};
class Distance
{

public:
Distance(Point xp1,Point xp2):
p1(xp1),p2(xp2)
{
double x =pl.GetX()-p2.GetY();

double y =p1.GetY()-p2.GetY();
double dis =sqrt(x*x+y*y);
}
double Getdis()
{
return dis;
}

private:
double dis;
Point p1,p2;

};
int main()
{
Point mp1(1,0),mp2(2,2);
Distance mdis(mp1,mp2);
cout<<"the distance is :"<<mdis.Getdis()<<endl;
}

Answer 1

double x =pl.GetX()-p2.GetY();这一句中把数字“1”打成字母“l”了