Point类求两点间距离 3种实现方法

//两点间距离 成员函数
#include<iostream>
#include<cmath> 
using namespace std;

class Point {
	public:
		Point(int x=0,int y=0):x(x),y(y){}
		float dist(Point &p);
	private:
		int x,y;
};

float Point::dist(Point &p1){
	double x=this->x-p1.x;
	double y=this->y-p1.y;
	return static_cast<float>(sqrt(x*x+y*y));
}

int main(){
	Point myp1(1,1),myp2(4,5);
	cout<<"The distance is: ";
	cout<<myp1.dist(myp2)<<endl;
	return 0;
} 

//两点间距离 成员函数
#include<iostream>
#include<cmath> 
using namespace std;

class Point {
	public:
		Point(int x=0,int y=0):x(x),y(y){}
		int getX(){return x;}
		int getY(){return y;}
	private:
		int x,y;
};

float dist(Point &p1,Point &p2){
	double x=p1.getX()-p2.getX();
	double y=p1.getY()-p2.getY();
	return static_cast<float>(sqrt(x*x+y*y));
}

int main(){
	Point myp1(1,1),myp2(4,5);
	cout<<"The distance is: ";
	cout<<dist(myp1,myp2)<<endl;
	return 0;
} 

//两点间的距离 友元函数
#include<iostream>
#include<cmath> 
using namespace std;

class Point {
	public:
		Point(int x=0,int y=0):x(x),y(y){}
		int getX(){return x;}
		int getY(){return y;}
		friend float dist(Point &p1,Point &p2);
	private:
		int x,y;
};

float dist(Point &p1,Point &p2){
	double x=p1.x-p2.x;
	double y=p1.y-p2.y;
	return static_cast<float>(sqrt(x*x+y*y));
}

int main(){
	Point myp1(1,1),myp2(4,5);
	cout<<"The distance is: ";
	cout<<dist(myp1,myp2)<<endl;
	return 0;
}