You have to initialize the vector of vectors to the appropriate size before accessing any elements. You can do it like this:

// assumes using std::vector for brevity

vector

This creates a vector of RR size CC vectors, filled with 0.

As it is, both dimensions of your vector are 0.

Instead, initialize the vector as this:

vector

for ( int i = 0 ; i < RR ; i++ )
matrix[i].resize(CC);
This will give you a matrix of dimensions RR * CC with all elements set to 0.