// ... здесь читаем размер и определяем количество вершин
Vertex *vlist = new Vertex[ vcount ];
// ... еще код ...
// В конце не забыть:
delete vlist;

// здесь читаем размер и определяем количество вершин
std::vector< Vertex > vlist;
Vertex v;
for (int i = 0; i < vcount; ++i ) {
    // Читаем очередную вершину в v
    vlist.push_back( v );
}
// И здесь ничего освобождать не нужно  =)

// Здесь читаем размер и определяем количество вершин
std::vector< Vertex > vlist( vcount );
for (int i = 0; i < vcount; ++i ) {
    // Читаем очередную вершину в v[ i ]
}
// И здесь ничего освобождать не нужно  =)

Before you worry about reading in this data, you need a place to store
it. That is where the S3dsMesh structure comes in. Each S3dsMesh structure
holds one triangular mesh. Because the file does not reveal how
many meshes there are total, you can call on the power of STL and
std::vector to create a place to store any number of meshes.

The rest of the data is contained in sub-chunks of the 0x4100 chunk.
(Yes, you can have sub-chunks of sub-chunks!) Because you do not
know how many vertices, faces, or materials there will be, you may want
to use a std::vector. This is essentially a resizable array. Using
std::vectors, you can add as many objects to your array as you like
without allocating or resizing it. If you aren’t sure about how to use
std::vectors, I suggest you skip to Appendix B.