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

vector V[] is just a fixed array; and so you can add/modify only till the upper limit. It is not a vector per se, and so has a fixed size limit. However vector< vector > V is a dynamic vector and its size can be increased dynamically.