无法访问指针矢量地图元素，

Question

into my private section I have :

vector<  vector<map<unsigned short int,col_data> > *> buffer_vectorS;
vector< map<unsigned short int,col_data> > * buffer_current;
map<unsigned short int,col_data> buffer_current_map;

( coldata is a simple structure: int, int, int, double )

Later I create a vector of map data, and save its pointer

vector<map<unsigned short int,col_data> > * buffer_vector = new vector<map<unsigned short int,col_data> >;
buffer_vectorS.push_back(buffer_vector);
buffer_current = buffer_vector;

Later I'd want to use the map element of the buffer_current to get-store data,

buffer_current_map = &buffer_current[index];

But this last does not compile.... I dont know how to write it... How can I access to an item of buffer_current? Can you help me ?

Answer 1

Do you mean:

buffer_current_map = (*buffer_vector)[index];

Be warned though, that will perform a copy operation on the map. You might want to access the map using pointer semantics:

map<unsigned short int,col_data> *buffer_current_map;
buffer_current_map = &(*buffer_vector)[index];

Then no copy will be done. Although, the pointer might be invalidated if a resize is done on the vector.