Re: Debug Assertion Failure

On Sat, 16 Jun 2007 01:21:55 -0700, katz911@gmail.com wrote:


If you need to have a binary file where you store several records of
the same size, you might want doing like so:

  // User record (fixed size)
  struct UserData
  {
    char UserName[ MAX_USER_NAME_CHARS ];
    char Password[ MAX_PASSWORD_CHARS ];
    long ID;
    ... etc. ...
  };

If you define UserData in this way, with only primitive data types
(char, long, etc. fixed-size arrays of these primitive types, *no*
pointers, *no* classes, like std::string), then you are allowed to
write records to file with a single call to fwrite, and read them back
with fread, and clear record with memset.

  UserData userData;

  // Clear record
  memset( &userData, 0, sizeof(userData) );
  // ...there is also the ::ZeroMemory Win32 function.

  // Read one record from file
  fread( &userData, sizeof(userData), 1, file );

etc.

(Note that I used 'char' because I think you are using std::string, so
maybe you are ignoring Unicode. But more correct Windows programming
style would consist in using TCHAR instead of 'char', to make the code
Unicode aware.)

Then you could copy the read data to the C++ class (more robust to
manage, because it has 'string' and not raw char arrays):

  // Member function to set fields
  // from UserData structure
  void Set( const UserData & userData )
  {
    UserName = userData.UserName;
    Password = userData.Password;
    ... etc.
  }

You might also define a construct like this:

  CUser_IO::CUser_IO( const UserData & userData )
    : UserName( userData.UserName ),
      Password( userData.Password ),
      etc...
  {
  }

and then write code like so:

  // Build the CUser_IO class from data
  // read from binary file
  CUser_IO myUser( userData );

  // Use myUser C++ class now
  ...

Moreover, I've read in your previous post that you are using VC++6.
VC++2005 has a better compiler, which can detect several error
conditions that VC++6 was unable to detect. Microsoft very kindly
offers the Express Edition of Visual C++ 2005; you might consider
downloading it and test the non-MFC part of your code (VC++2005
Express does not support MFC or ATL); maybe the new smarter and more
advanced VC++2005 compiler can help you better localize the bug in
your code.

Moreover, if you use VC++6 and STL classes, you may download STLport
and use it instead of VC++6 STL implementation:

 http://www.stlport.org

or apply Dinkumware's patches to VC++6 STL:

 http://www.dinkumware.com/vc_fixes.html

MrAsm