一 场景

• windows下获取磁盘容量和可用空间，可通过 GetDiskFreeSpace 系列 API：
  • GetDiskFreeSpaceA
  • GetDiskFreeSpaceW
  • GetDiskFreeSpaceExA
  • GetDiskFreeSpaceExW
• 后缀解释
  • A = ASCII非宽字节版本
  • W = 宽字节版本
  • Ex = 函数扩展版本

二 GetDiskFreeSpace

• 语法

BOOL GetDiskFreeSpaceA(
  LPCSTR  lpRootPathName,
  LPDWORD lpSectorsPerCluster, // 每簇扇区数
  LPDWORD lpBytesPerSector,  // 每扇区字节数
  LPDWORD lpNumberOfFreeClusters, // 可用簇数
  LPDWORD lpTotalNumberOfClusters // 总簇数
);

BOOL GetDiskFreeSpaceW(
  LPCWSTR lpRootPathName,
  LPDWORD lpSectorsPerCluster,
  LPDWORD lpBytesPerSector,
  LPDWORD lpNumberOfFreeClusters,
  LPDWORD lpTotalNumberOfClusters
);

BOOL GetDiskFreeSpaceExA(
  LPCSTR          lpDirectoryName,
  PULARGE_INTEGER lpFreeBytesAvailableToCaller, // 对调用者的磁盘可用字节数
  PULARGE_INTEGER lpTotalNumberOfBytes, // 对调用者的磁盘总字节数
  PULARGE_INTEGER lpTotalNumberOfFreeBytes // 磁盘可用字节数
);

BOOL GetDiskFreeSpaceExW(
  LPCWSTR         lpDirectoryName,
  PULARGE_INTEGER lpFreeBytesAvailableToCaller,
  PULARGE_INTEGER lpTotalNumberOfBytes,
  PULARGE_INTEGER lpTotalNumberOfFreeBytes
);

• 条件宏

#ifdef UNICODE
#define GetDiskFreeSpace  GetDiskFreeSpaceW
#else
#define GetDiskFreeSpace  GetDiskFreeSpaceA
#endif // !UNICODE

#ifdef UNICODE
#define GetDiskFreeSpaceEx  GetDiskFreeSpaceExW
#else
#define GetDiskFreeSpaceEx  GetDiskFreeSpaceExA
#endif // !UNICODE

三 举例

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

using namespace std;

int main(){
    
    
  DWORD sectorsPerCluster = 0;
  DWORD bytesPerSector = 0;
  DWORD numberOfFreeClusters = 0;
  DWORD totalNumberOfClusters = 0;
  if (GetDiskFreeSpace(L"F:", &sectorsPerCluster, &bytesPerSector, 
                       &numberOfFreeClusters, &totalNumberOfClusters)){
    
    
    cout << "GetDiskFreeSpace:" << endl;
    cout << "SectorsPerCluster\t " << sectorsPerCluster << endl;
    cout << "BytesPerSector\t " << bytesPerSector << endl;
    cout << "NumberOfFreeClusters\t " << numberOfFreeClusters << endl;
    cout << "TotalNumberOfClusters\t " << totalNumberOfClusters << endl;
  }


  ULARGE_INTEGER avail = {
    
    0}; 
  ULARGE_INTEGER total = {
    
    0};
  ULARGE_INTEGER free = {
    
    0};
  if (GetDiskFreeSpaceEx(L"F:", &avail, &total, &free)) {
    
    
    cout << "GetDiskFreeSpaceEx:" << endl;
    cout << "TotalNumberOfBytes\t " << total.QuadPart << endl;
    cout << "TotalNumberOfFreeBytes\t " << free.QuadPart << endl;
    cout << "FreeBytesAvailableToCaller\t " << avail.QuadPart << endl;
  }

  cin.get();
  return 0;
}

• 结果

GetDiskFreeSpace:
SectorsPerCluster        8
BytesPerSector           512
NumberOfFreeClusters     50446681
TotalNumberOfClusters    87006207

GetDiskFreeSpaceEx:
TotalNumberOfBytes         356377423872
TotalNumberOfFreeBytes     206629605376
FreeBytesAvailableToCaller 206629605376

• 分析
  • 根据 GetDiskFreeSpace 调用结果计算：
    • 磁盘可用字节数: 8 * 512 * 50446681 = 206 629 605 376 Bytes
    • 磁盘总字节数: 8 * 512 * 87006207 = 356 377 423 872 Bytes
  • GetDiskFreeSpaceEx 直接获取到最终的字节数，更加方便。
• F盘容量
  

四 其他

• 非windows， 可查阅 statfs