#include <vector>
#include <cassert>
using namespace std;
struct Vec2
{
    float a;
    float b;
};

int main()
{
    int assert_s[ sizeof(Vec2) == 2*sizeof(float) ? 1 : -1 ];
    typedef vector<Vec2> Vector;
    Vector v(32);
    float *first=static_cast<float*>(static_cast<void*>(&v[0]));
    for(Vector::size_type i,size=v.size();i!=size;++i)
    {
        assert((first+i*2) == (&(v[i].a)));
        assert((first+i*2+1) == (&(v[i].b)));
    }
    assert(false != false);
}