IDE：vs2015

1 #include<unordered_map>
 2 #include<string>
 3 #include<vector>
 4 #include<iostream>
 5 
 6 using namespace std;
 7 
 8 class Point
 9 {
10 public:
11     Point(int id, int x, int y) :id_(id), x_(x), y_(y)
12     {
13         cout << " id_ = " << id_ << " x_ = " << x_ << " y_ = " << y_ << endl;
14     }
15 
16     Point(const Point& p)
17     {
18         this->id_ = p.id_;
19         this->x_ = p.x_;
20         this->y_ = p.y_;
21     }
22 
23     ~Point() {};
24     int id_;
25 
26 private:
27     int x_, y_;
28 };
29 
30 void dosomething(Point &points_)
31 {
32     unordered_map<int, Point> unordmap_points;
33     if (unordmap_points.find(points_.id_) == unordmap_points.end())
34     {
35         cout << "hello!" << endl;
36         unordmap_points.insert(make_pair(points_.id_, points_));
37     }
38     else
39     {
40         
41         //unordmap_points[points_.id_] = points_;
42         cout << "goo-bye" << endl;
43     }
44 }
45 
46 int main()
47 {
48     vector<Point> points;
49     const int maxnum[5] = {0,1,2,3,4};
50     for (int i : maxnum)
51     {
52         points.push_back(Point(i, i, i));
53     }
54     
55     for (int i : maxnum)
56     {
57         dosomething(points[i]);
58     }
59     return 1;
60 }

取消注释41行后：编译器报错

：   

错误 C2512 “Point::Point”: 没有合适的默认构造函数可用 TEST1 d:\program files (x86)\microsoft visual studio 14.0\vc\include\tuple 1180

请问该怎么改？

 另外，个人觉得 函数 dosomething() 中的 else情形是多余的？不知道为什么，看到某底层代码有else，搞不懂，来个大神解释一波哈？