I was wondering why can't I have a multi vectors in C ++ /please take a look at this example, it's not working though.

there are only two parts to the code, foo function to manipulate the vector and the main function to echo them.

typedef vector< vector<double> > MyVec;

MyVec foo() {
    MyVec v;    

    for (int index=0; index < 2; index ++) {
        for (int j=0; j<5; j++) {
            v[index][j];
        }   
    }

    return v;
}

int main () {
    MyVec z = foo();

    for (int i = 0; i < z.size(); i++) {
        cout << z[i][1];                    
    }

    return 0;
}