c++ finding distance between 2 points - c++

Question

In my test program I have two points, and I want to find distance between them with my distancefrom. But I get answer 0.
Why does it give 0?
How can I fix it?
Point<2> v1;
// this should have {0.0, 0.0}
Point<2> v3 { list{2.0,3.0} };
float f = v1.distanceFrom(v3);
cout << f << endl;
I have a point.h file.
#ifndef POINT_H
#define POINT_H
#include <iostream>
#include <list>
#include <sstream>
#include <string>
using std::stringstream;
#include <cmath>
using namespace std;
template<unsigned short n>
class Point {
public:
list <float> coords = {0.0};
Point <n>() = default;
Point <n>(list<float> coords){
if (coords.size()!=n) {
throw string ("Vale koordinaatide arv");
}
this-> coords=coords;
}
string toString(){
string sone;
ostringstream ss;
sone.append("(");
auto it3= coords.begin();
while ((it3) != coords.end()){
ss << (*it3);
sone.append(ss.str());
ss.str("");
sone.append(",");
++it3;
}
sone.pop_back();
sone.append(")");
return sone;
}
float distanceFrom (Point <n> v){
float s=0;
list<float> coords;
auto it1= coords.begin();
auto it2= v.coords.begin();
while ((it1) != coords.end()){
s+=(*it1 -*it2)*(*it1-*it2);
it1++;
it2++;
}
return sqrt(s);
}
friend std::ostream& operator <<(std::ostream& out, const Point<n>& v)
{
out << "("<<"Test"<<")";
return out;
}
};
#endif

Answer 1

First, your coords list does not know you want its size to be n. Its size after default initialization like the following is 1:
list <float> coords = {0.0};
The proper way to construct it would be:
list <float> coords = list <float> (n, 0.0);
Second, you allocate a new coords inside the function distanceFrom:
list<float> coords;
This shadows the real coords of the point which you in fact want to use. Remove that line, and you will be fine.

Answer 2

#include<iostream>
#include<cstdlib>
#include<cmath>
using namespace std;
class pointDistance{
int x, y;
public:
pointDistance (int a, int b){
x =a;
y =b;
}
void pointShow(){
cout<<"The Point is ("<<x<<","<<y<<")"<<endl;
}
friend void Distance(pointDistance , pointDistance);
};
//formula of distance between two points:
//d =((x1^2 - x2^2) + (y1^2 - y2^2))^1/2
void Distance(pointDistance o1, pointDistance o2)
{
// pointDistance o3;
int d1,d2;
d1 = (o1.x -o2.x)*(o1.x -o2.x);
d2 = (o1.y - o2.y)*(o1.y - o2.y);
cout<<"So the distance between two point is "<< sqrt(d1+d2)<<endl;
}
int main(){
pointDistance one(4,5);
one.pointShow();
pointDistance two(0,6);
two.pointShow();
Distance(one, two);
return 0;
}