I wrote two `for` loops and expected to see if they would output every value in a vector called `data`, but it doesn't work. There is an error relating to `data[i].at(j)` that I don't quite understand.

```
vector<int> data; //it is filled with some integers with x rows and y columns

for ( int i = 0; i < data.size(); ++i) {
    for ( int j = 0; j < col; ++j ) {
        cout << data[i].at(j) << ' ';
    }

    cout << endl;
}

```

I've also tried this method, but it doesn't work either. `data.at(i).at(j)` has an error.

```
for ( int i = 0; i < data.size(); ++i ) {
    for ( int j = 0; j < col; ++j ) {
        cout << data.at(i).at(j) << ' ';
    cout << endl;
}

```

Can either of these work with a minor fix or don't they work at all?