vector max_size calculation, how?

#include "stdafx.h"
#include <iostream>
#include <vector>
#include "conio.h"
int main ()
{
	typedef struct
	{
		int iArr[10];
	}BIGSTRUCT;

	BIGSTRUCT st;
  std::vector<BIGSTRUCT> myvector;
  int ii = sizeof(BIGSTRUCT);
  std::cout << "max_size: " << (int) myvector.max_size() << '\n';
  _getch();
  return 0;
}

I am using following code to get maximum vector I can allocate; If the size of iArr is 1, then I am getting it 1,073,741,823; But if I increase the size to 10, it is 1,073,741,82;
http://stackoverflow.com/questions/4321040/c-vectors-of-objects-and-pointers?rq=1[^]
http://stackoverflow.com/questions/3813124/c-vector-max-size[^]
I have too many confusions here:
1) how this number is coming? Ho wit is calculated?

Now, if I am on a 32bit machine, with 2GB RAM, and if I have a vector of size say 170,000,000 members, what is the maximum size of each member do I have to have so I will not go out of memory?

Thanks

Tags: C++, STL