How to use vector::push_back()` with a struct?

Question

How can I push_back a struct into a vector?

struct point {     int x;     int y; };  std::vector<point> a;  a.push_back( ??? ); 

Answer 1

point mypoint = {0, 1}; a.push_back(mypoint); 

Or if you're allowed, give point a constructor, so that you can use a temporary:

a.push_back(point(0,1)); 

Some people will object if you put a constructor in a class declared with struct, and it makes it non-POD, and maybe you aren't in control of the definition of point. So this option might not be available to you. However, you can write a function which provides the same convenience:

point make_point(int x, int y) {     point mypoint = {x, y};     return mypoint; }  a.push_back(make_point(0, 1)); 

Answer 2

point p; p.x = 1; p.y = 2;  a.push_back(p); 

Note that, since a is a vector of points (not pointers to them), the push_back will create a copy of your point struct -- so p can safely be destroyed once it goes out of scope.