Difference between vector V[] and vector< vector> > V

Question

vector V[] and vector< vector > V both are 2D array.

But what is the differenc

Answer 1

One difference would be that although both can be initialized in the same way, e.g.

vector V1[]        {{1,2,3}, {4,5,6}};
vector> V2  {{1,2,3}, {4,5,6}};

and accessed

cout << V1[0].back() << endl;
cout << V2[0].back() << endl;

the V1 can't grow. You cannot make V1.push_back(...) as its not a vector object. Its just an array. Second one is dynamic. You can grow it as you please.