Correctly passing a vector by reference or pointer

Question

I try to (basically) make a Setter method for a std::vector (its D3D10 rendering)

void GraphicsClass::BeginFrame(vector<LightClass> const &vlights)
{
    lights = vlights;

where lights is a private member of GraphicsClass, declaration:

vector<LightClass> lights;

Now, the properties of the array get copied; but the elements lights[0], lights[1] etc contain garbage. I checked this using the Visual Studio debugger.

I could obviously work around by using

void GraphicsClass::BeginFrame(vector<LightClass> const &vlights) {
    int size = vlights.size();
    int i;
    lights.resize(size);
    for (i = 0; i < size; i++)
       lights[i] = vlights[i];

But I don't like that I don't understand this topic, and this code seems a good bit slower.

Thanks in advance for answers!

LightClass as requested:

class LightClass
{
public:
LightClass(void);
~LightClass(void);
void SetDiffuseColor(float, float, float, float);
void SetDirection(float, float, float);

D3DXVECTOR4 GetDiffuseColor();
D3DXVECTOR3 GetDirection();

 private:
D3DXVECTOR4 m_diffuseColor;
D3DXVECTOR3 m_direction;
};

both the constructor and the destructor are empty which is a mistake (I copied this from classes which I only create pointers to. like Type *thing. I'm new to OOP)

I will probably change the vector to vector though.

Answer 1

You need to have implemented a copy constructor for LightClass, not just operator= (as in your workaround).