c++ - 2D vector of unknown size -

i defined empty vector of vectors :

vector< vector<int> > v;

how fill empty vector vector of size 2 integers ( input ) each iteration of while loop?

while ( cin >> x >> y ) {   //.... }

will 1 work? or what's best , elegant / effective way of doing it?

while ( cin >> x >> y ) {    vector<int> row;    row.push_back( x );    row.push_back( y );    v.push_back( row ); }

as pointed out jerrycoffin, better use :

struct point {     int x;     int y; };

and might overload output operator

std::ostream& operator<< (std::ostream& o,const point& xy){     o << xy.x << " " << xy.y;     return o; }

and similar input operator (see e.g. here). , can use this:

int main() {     point xy;     std::vector<point> v;     v.push_back(xy);     std::cout << v[0] << std::endl;     return 0; }

Look