what does this error mean?

The error:

Code:

CFileInfo.cpp: In method `CFileInfo::CFileInfo(const CFileInfo &)':
CFileInfo.cpp:26: passing `const CFileInfo' as `this' argument of `void CFileInfo::getFileName(string *)' discards qualifiers
CFileInfo.cpp:27: passing `const CFileInfo' as `this' argument of `size_t CFileInfo::getFileSize()' discards qualifiers

And the function in question (it's a copy constructor):

Code:

CFileInfo::CFileInfo(const CFileInfo &CopySource)
{
  CopySource.getFileName(&FileName);  // sets FileName equal to string FileName in CopySource
  FileSize = CopySource.getFileSize();  // sets FileSize equal to size_t FileSize in CopySource
}  // end CFileInfo(CFileInfo const &CopySource)

getFileName() and getFileSize() need to be const.

It works now. . .can anyone tell me why?

You took CopySource as a const parameter, meaning that only const functions could be called on CopySource. When non-const member functions are called, a compiler error message is issued.