vector subscript out of range during compiling

Question

int i = 0;
int j = 0;

vector<vector<int>> normal;
vector< vector<int> >::iterator row;
vector<int>::iterator col;

for (i = 1; i < 10; i++) {
    for (j = 1; j < 10; j++) {
         normal[i].push_back(j);

    }
}

Can someone explain me what l am doing wrong? during my compiling I got the error "Vector subscript out of range"

Answer 1

You never add any elements to normal before trying to use normal[i].