[WinAPI] Cum aflu dimensiunea unui fisier?

[Silviu Ardelean]

Intrebare: Cum aflu dimensiunea unui fisier?

Raspuns: O metoda este folosind functia FindFirstFile.

Exemplu

Code: Select all

ULONGLONG GetFileSize(LPCTSTR szFilePath)
{
   // NOTE: This is a draft example. 
   // Not all tests are performed, e.g. if szFilePath is valid (see FindFirstFile documentation).

   ULONGLONG nSize = 0;
   WIN32_FIND_DATA findData = {0};
   HANDLE hFind = ::FindFirstFile(szFilePath, &findData);
   if(INVALID_HANDLE_VALUE != hFind)
   {
      ULARGE_INTEGER liSize = {findData.nFileSizeLow, findData.nFileSizeHigh};
      nSize = liSize.QuadPart;
      ::FindClose(hFind);
   }
   return nSize;
}

Vezi si:

• [MSDN] FindFirstFile Function
• [C++] Detectia dimensiunii unui fisier

[Ovidiu Cucu]

Raspuns
Pentru aflarea dimensiunii unui fisier se pot utiliza urmatoarele functii WinAPI:

1. GetFileSize
   Exemplu

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   DWORD _GetFileSize(LPCTSTR pszFileName, ULONGLONG& nSize)
   {
      DWORD dwRet = NO_ERROR;
      DWORD dwDesiredAccess = 0; // open just to query info
      HANDLE hFile = ::CreateFile(pszFileName,
         dwDesiredAccess, 0, NULL, OPEN_EXISTING,
         0, NULL);
   
      if(INVALID_HANDLE_VALUE != hFile)
      {
         DWORD dwFileSizeHi = 0;
         DWORD dwFileSizeLo = ::GetFileSize(hFile, &dwFileSizeHi);
         if(INVALID_FILE_SIZE == dwFileSizeLo)
         {
            // check if failed or really is a good low-part value
            dwRet = ::GetLastError();
         }
         if(NO_ERROR == dwRet)
         {
            LARGE_INTEGER liSize = {dwFileSizeLo, dwFileSizeHi};
            nSize = liSize.QuadPart; // file size in bytes
         }
         ::CloseHandle(hFile);
      }
      else
      {
         dwRet = ::GetLastError();
      }
      return dwRet; // NO_ERROR if succeeded
   }

2. GetFileSizeEx
   Exemplu

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   DWORD _GetFileSizeEx(LPCTSTR pszFileName, ULONGLONG& nSize)
   {
      DWORD dwRet = NO_ERROR;
      DWORD dwDesiredAccess = 0; // open just to query info
      HANDLE hFile = ::CreateFile(pszFileName,
         dwDesiredAccess, 0, NULL, OPEN_EXISTING,
         0, NULL);
   
      if(INVALID_HANDLE_VALUE != hFile)
      {
         LARGE_INTEGER liSize = {0};
         if(::GetFileSizeEx(hFile, &liSize))
            nSize = liSize.QuadPart; // file size in bytes
         else
            dwRet = ::GetLastError();
         ::CloseHandle(hFile);
      }
      else
      {
         dwRet = ::GetLastError();
      }
      return dwRet; // NO_ERROR if succeeded
   }

3. FindFirstFile
   Vezi postul precedent.

Resurse

• [MSDN] GetFileSize Function
• [MSDN] GetFileSizeEx Function
• [MSDN] FindFirstFile Function

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[mesajflaviu]

O alta metoda de a afla dimensiunea unui fisier fara a-l deschide, este folosind metoda CFile::GetStatus, versiunea statica.
Exemplu:

Code: Select all

	CString sPath(_T("D:\\Temp\\myfile.txt"));
	CFileStatus status;
	CFile::GetStatus(sPath, status);
	ULONGLONG dwFileSize = status.m_size;

Mai mult, cu ajutorul acestei metode putem afla pe langa marimea fisierului, informatii cu privire la data crearii/modificarii/accesarii, precum si atributele fisierului.