#ifndef POINT_H_
#define POINT_H_
using namespace std;
class Point
{
private:
    int x;
    int y;
public:
    Point(int x=0,int y=0):    x(x),y(y)
    {
        cout<<"."<<endl;
    }
    void in();
    void out();
    double des(Point,Point);
};
#endif

#include<iostream>
#include<math.h>
#include"point.h"
int main()
{
    Point p1,p2;
    p2.in();
    p1.out();
    p2.out();
    cout<<des(p1,p2);
        return 0;
}
void Point::in ()
{
    cin>>x>>y;
}
void Point::out()
{
    cout<<"("<<x<<","<<y<<")"<<endl;
}
double Point::des(Point p1,Point p2)
{
    int a=0;
    a=sqrt(pow(p1.x-p2.x,2)+pow(p1.y-p2.y,2));
    return a;
}

就是那里错的，怎么改呢？

明白了，谢谢大神相助！