我如何获得指针值？ C++

Question

So I want to get the value from an item of vector. The vector contains Line items. Line has to pointers Vertex *p1 and Vertex *p2. and Vertex has fields of x and y. How can i make my code give me the values of those x and y?

for(Line<Vertex> line : lines){
    painter.drawLine(line.p1->x + 5, line.p1->y + 5, line.p2->x + 5, line.p2->y + 5);
}

Line class is as following:

template<class T>
class Line {

public:

    T *p1;
    T *p2;

    Line (T *v1, T *v2)
        : p1(v1),
          p2(v2)
    {}

    Line (const Line& l){
        if(this != &l){
            p1 = l.p1;
            p2 = l.p2;
        }
    }

     Line& operator= (const Line& l) {
        if (this == &l)
            return *this;
        p1 = l.p1;
        p2 = l.p2;
        return *this;
    }

    ~Line (){
    }
};

Vertex class:

class Vertex {

public:


    float x = 0;
    float y = 0;

    Vertex() = default;
    Vertex(float nx, float ny);

    float distanceFrom(Vertex v);

};

Main:

std::vector<Line<Vertex>> lines;
Vertex *firstPoint;
Vertex *secondPoint;
bool firstPointChosen = false;
bool secondPointChosen = false;

if(!firstPointChosen){
        for(Vertex vertex : vertices){
            firstPoint = &vertex;
            firstPointChosen = true;
            break;
        }
    }
    else{
        for(Vertex vertex : vertices){
            secondPoint = &vertex;
            secondPointChosen = true;
            break;
        }
    }

if(firstPointChosen && secondPointChosen){
    Line<Vertex> line(firstPoint, secondPoint);
    lines.push_back(line);
    update();
    firstPointChosen = false;
    secondPointChosen = false;
}
for(Line<Vertex> line : lines){
        painter.drawLine(line.p1->x + 5, line.p1->y + 5, line.p2->x + 5, line.p2->y + 5);
    }

How do i get make the first block of code return the values of x and y for each line that i have added to the lines vector?

Currently it doesn't return anything or i'm missunderstanding something.

EDIT: The main class is alot bigger, but it is called in that order. First it chooses the first vertex, then second. If both of them are selected it makes a new Line with those two vertices, but for some reason they get no values or something.

Answer 1

it should be the other way:

pointed value of line and member of vertex

for(Line<Vertex> line : lines){
    painter.drawLine(line->p1.x + 5, line->p1.y + 5, line->p2.x + 5, line->p2.y + 5);
}

if the class has

T* pointerToMember;
T member;

you should get pointed member with -> and member with .

obj->pointerToMember;
obj.member;