GetCompressedFileSize

The GetCompressedFileSize function retrieves the actual number of bytes of disk storage used to store a specified file. If the file is located on a volume that supports compression, and the file is compressed, the value obtained is the compressed size of the specified file. If the file is located on a volume that supports sparse files, and the file is a sparse file, the value obtained is the sparse size of the specified file.

DWORD GetCompressedFileSize(
  LPCTSTR lpFileName,     // file name
  LPDWORD lpFileSizeHigh  // high-order DWORD of file size
);

Parameters

lpFileName

[in] Pointer to a null-terminated string that specifies the name of the file.

Do not specify the name of a file on a nonseeking device, such as a pipe or a communications device, as its file size has no meaning.

lpFileSizeHigh

[out] Pointer to a variable that receives the high-order DWORD of the compressed file size. The function's return value is the low-order DWORD of the compressed file size.

This parameter can be NULL if the high-order DWORD of the compressed file size is not needed. Files less than 4 gigabytes in size do not need the high-order DWORD.

Return Values

If the function succeeds, the return value is the low-order DWORD of the actual number of bytes of disk storage used to store the specified file, and if lpFileSizeHigh is non-NULL, the function puts the high-order DWORD of that actual value into the DWORD pointed to by that parameter. This is the compressed file size for compressed files, the actual file size for noncompressed files.

If the function fails, and lpFileSizeHigh is NULL, the return value is -1. To get extended error information, call GetLastError.

If the return value is -1 and lpFileSizeHigh is non-NULL, an application must call GetLastError to determine whether the function has succeeded (value is NO_ERROR) or failed (value is other than NO_ERROR).

Remarks

An application can determine whether a volume is compressed by calling GetVolumeInformation, then checking the status of the FS_VOL_IS_COMPRESSED flag in the DWORD value pointed to by that function's lpFileSystemFlags parameter.

If the file is not located on a volume that supports compression or sparse files, or if the file is not compressed or a sparse file, the value obtained is the actual file size, the same as the value returned by a call to GetFileSize.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Windows 95/98: Unsupported.
  Header: Declared in Winbase.h; include Windows.h.
  Library: Use Kernel32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT/2000.

See Also

File Systems Overview, File System Functions, GetFileSize, GetVolumeInformation