Vector Vector C ++ Hi, I do not understand the syntax of nested vectors to simulate an array, I have the following code.

```
vector< vector< float> > myvector (n, vector < float> (2));
```

But I do not quite understand how it works, especially where you specify the size of the vectors and the vectors in it, if you want to make a resize so that my vector vector has specified dimensions how can I resize internal vectors? Something like changing `vec [10] [2]`

to `vec [10] [5]`

(changing the second dimension)

In addition to how to make copies with multidimensional vectors something like:

```
vector< int> myvector (myVectorToCopy, myVectorToCopy+myVectorToCopy.size());
```

But with several dimensions. Thanks.

`vector<vector<float>>`

means you are creating a vector which contains a vector of floats. The constructor argument means you are creating a vector of size `n`

where each element of vector is a vector of floats having size 2.

To resize the `vector<vector<float>>`

:

```
for (int i = 0; i < n; ++i)
A[i].resize(newSize);
```

Alternatively you could use:

```
A.assign(n,vector<float>(newSize));
```

To make a copy of multidimensional vector use constructor:

```
vector<vector<float>> B(A);
```