Thread: class problem (init. struct, itierator for 2d array)

Hey guys, I'm having a bit of trouble with making this class for a 3d cube. I have simply made a few functions to build the infrastructures so far, so I have a purpose for most of the things in there, even if they aren't used yet.
I am strugling in a few different areas in which I will outline for you.

1. How can I initialize a dynamic structure in a class. // haven't found much on it, not in classes
2. how can I initialize a dynamic array in a class. //I don't want to specify the size of cubeNumber[amount] untill constructor.
3. How can I use iterators for multidimensional vectors? // This just confuses me

Now I have never made a structure in a class before. Just how am I supposed to initialize it, int the private: area, or in the constructor?
here is the class

Code:

using namespace std;

class cubes
{
public:
	// cube amount, defualt is 20
	cubes(int input);
	// add a cube, with a vector of it's vertices
	void addCube(vector<vector<float>> input, int input2);
	// get the vertices of a cube
	vector<float> getVertices(int input);  // input cube #
	// shift the cube x amount of units in x, y, and z dirctions
	void shiftCube(float input1, float input2, float input3, int input4);
private:
	struct cubeIndex
	{
		// clockwise on top, then clockwise on bottom
		vector<vector<float>> vertices;  // there are 8 corners to a cube
		// for future functions of class
		vector<float> specs;     
	// lets make an array of structures so that we can have a struct for each cube
	} cubeNumber[20];  // **** how do I make this dynamic? ******
	// if cubeId is over bounds, will return error vector *comint soon*
	vector<float> errorVector;
};


void cubes::addCube(vector<vector<float>> input, int input2)
{
	cubeNumber[input2].vertices = input;
	// make room for the specs, we will calculate them when get specs is called
	// this way we don't have to worry about it when they call cubes::getSpecs(int cubeNumber)
	cubeNumber[input2].specs.push_back(0);
	cubeNumber[input2].specs.push_back(0);

}
void cubes::shiftCube(float input1, float input2, float input3, int input4)
{
	/* ****** how would I use an iterator here, I know that it is supposed to help
	contain memory leaks, and is simply a better method than using the variable in the
	for statement ********* */
	int b = 0;
	int k = 0;
	// lets shift all vertices
	for(int i = 0, i <=8, i += 3)
	{
		// x
		cubeNumber[input4].vertices[b][k] += input1;
		// y
		cubeNumber[input4].vertices[b][(k+1)] += input2;
		// z
		cubeNumber[input4].vertices[b][(k+2)] += input3;
		b++;
		k++;
		
	}
}

Also if anyone could lead me to a good article on dynamic programming, that would be greatly appreciated.

Thanks for your time and effort,

Joe