seeing if stl vector really keeps data contiguous

stlVectorTest

#include <vector>
#include <iostream>
using namespace std;

typedef float T;

int main()
{
        int data_size = 512;
        vector<T *> data;
        int num_data = 512;
        for(int i = 0; i < num_data; i++)
        {
                T * el = (T *)malloc(sizeof(T) * data_size);
                for(int j = 0; j < data_size; j++)
                {
                        el[j] = i*data_size + j;
                }
                data.push_back(el);
        }

		bool isItContiguous = true;
        T * ptr = data[0];
        for(int i = 0; i < num_data; i++)
        {
                for(int j = 0; j < data_size; j++)
                {
                        if( *(ptr+i*data_size+j) != data[i][j] )
						{
								cout <<  i << "," << j << ": " << *(ptr+i*data_size+j) << "," << data[i][j] << " " << endl;
							isItContiguous = false;
							break;
						}
                }
				if(!isItContiguous)
					break;
        }

		if(isItContiguous)
		{
			printf("YES, allocated %ld kbytes contiguously.\n", sizeof(T)*data_size*num_data/1024);
		}
		else
		{
			printf("NO\n");
		}

		// free up
        for(int i = 0; i < num_data; i++)
        {
                T * el = data[i];
                free(el);
        }

		
        vector<vector<T > > ddata;
		for(int i = 0; i < num_data; i++)
        {
			vector<T> el;
			el.resize(data_size);
                for(int j = 0; j < data_size; j++)
                {
                        el[j] = i*data_size + j;
                }
                ddata.push_back(el);
        }

		isItContiguous = true;
        ptr = &(ddata[0][0]);
        for(int i = 0; i < num_data; i++)
        {
                for(int j = 0; j < data_size; j++)
                {
                        if( *(ptr+i*data_size+j) != ddata[i][j] )
						{
							cout <<  i << "," << j << ": " << *(ptr+i*data_size+j) << "," << ddata[i][j] << " " << endl;
							isItContiguous = false;
							break;
						}
                }
				if(!isItContiguous)
					break;
        }

		if(isItContiguous)
		{
			printf("YES, allocated %ld kbytes contiguously.\n", sizeof(T)*data_size*num_data/1024);
		}
		else
		{
			printf("NO\n");
		}
        return 0;
}