Free Disk Space - WinAPI

#include <iostream>
#include <windows.h>

using namespace std;

int main()
{
    unsigned long long TotalBytes, FreeBytes;

    GetDiskFreeSpaceEx ("C:\\", //diretório
                       NULL,
                       &TotalBytes,
                       &FreeBytes);

    float fLivre = FreeBytes/(float)1073741824;
    float fTotal = TotalBytes/(float)1073741824;
    cout << "Espaco Livre(GB) : " << fLivre << endl;
    cout << "Espaco Total(GB) : " << fTotal << endl;
    return 0;
}