What's the size of that vector, anyway?(rachelbythebay.com)

  vector<int> v{3} size() 1
  vector<string> v{3} size() 3
  vector<int> v{0} size() 1
  terminate called after throwing an instance of 
  'std::logic_error'
    what():  basic_string::_M_construct null not valid
  Aborted (core dumped)