How to work is that C++ Language

Question

vector<vector<char> > a(5,vector<char>(5,' '));

Answer 1

<a> is a `vector` that is defined as container for `vector` of `char`. <a> is initialized with 5 `vector` of `char`, each of which contains 5 space character.

Answer 2

vector <char> x (5,’ ‘);
vector<vector<char>>a(5,x);