FIX: CFile::GetFileName() Always Returns CString w/Zero Length

The information in this article applies to:

• The Microsoft Foundation Classes (MFC) included with: Microsoft Visual C++, 32-bit Edition, version 4.0

SYMPTOMS

If you call CFile::GetFileName(), it will return a CString with the correct file name. However, if you call GetLength() on the CString, it will return 0.

CAUSE

The MFC function CFile::GetFileName() writes directly to the CString's character pointer. However, it doesn't set the CString's size before returning from this function.

RESOLUTION

Call CString::ReleaseBuffer() after calling CFile::GetFileName().

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug was corrected in Visual C++ 4.1.

MORE INFORMATION

Sample Code

void CTestDoc::Serialize(CArchive& ar)

   if (ar.IsStoring())
   {
      // TODO: add storing code here
   }
   else
   {
      CFile* fp = ar.GetFile ();
      ASSERT (fp);
      CString fname = fp->GetFileName ();
      // this line is needed to set the size of CString
      fname.ReleaseBuffer ();
      int nLength = fname.GetLength();
   }