GetDiskFreeSpace函式和GetDiskFreeSpaceEx函式，主要是用來計算磁碟的各種容量，具體能計算什麼，程式碼中註釋得很詳細

<pre name="code" class="cpp">#include <Windows.h>
#include <iostream>
using namespace std;
int main()
{
    //得出磁碟的可用空間
    DWORD dwTotalClusters;//總的簇
    DWORD dwFreeClusters;//可用的簇
    DWORD dwSectPerClust;//每個簇有多少個扇區
    DWORD dwBytesPerSect;//每個扇區有多少個位元組
    BOOL bResult = GetDiskFreeSpace(TEXT("C:"),&dwSectPerClust, &dwBytesPerSect, &dwFreeClusters, &dwTotalClusters);
    if(bResult){
        cout << "使用GetDiskFreeSpace函式獲取磁碟空間資訊" << endl;
        cout << "總簇數量: " << dwTotalClusters << endl;
        cout << "可用的簇: " << dwFreeClusters << endl;
        cout << "每個簇有多少個扇區: " << dwSectPerClust << endl;
        cout << "每個扇區有多少個位元組: " <<  dwBytesPerSect << endl;
        cout << "磁碟總容量: " <<  dwTotalClusters * (DWORD64)dwSectPerClust * (DWORD64)dwBytesPerSect << endl;
        cout << "磁碟空閒容量: " << dwFreeClusters * (DWORD64)dwSectPerClust * (DWORD64)dwBytesPerSect << endl;
    }
    cout << "\n\n" << endl;

    DWORD64 qwFreeBytes, qwFreeBytesToCaller, qwTotalBytes;
    bResult = GetDiskFreeSpaceEx(TEXT("C:"), 
	(PULARGE_INTEGER)&qwFreeBytesToCaller, 
	(PULARGE_INTEGER)&qwTotalBytes, 
	(PULARGE_INTEGER)&qwFreeBytes);
    if(bResult){
        cout << "使用GetDiskFreeSpaceEx函式獲取磁碟空間資訊" << endl;
        cout << "磁碟總容量: " <<  qwTotalBytes << endl;
        cout << "可用的磁碟空閒容量: " << qwFreeBytes << endl;
        cout << "磁碟空閒容量: " << qwFreeBytesToCaller << endl;
    }
    system("pause");
}