Assumption: The filename contains no more than 12 characters.

If your operating system supports long filenames, 12-character buffers might not have enough space for all the characters in the filename. Consider the following code snippet, in which the buffer is assumed to be 12 characters long:

char szFile [12] = "\0";



// Fill out the OPENFILENAME structure to support a template and
a hook.

OpenFileName.lStructSize = sizeof (OPENFILENAME);

OpenFileName.hwndOwner = hWnd;

OpenFileName.hInstance = g_hInst;

OpenFileName.lpstrFilter = NULL;

OpenFileName.lpstrCustomFilter = NULL;

OpenFileName.nMaxCustFilter = 0;

OpenFileName.nFilterIndex = 0;

OpenFileName.lpstrFile = szFile;

OpenFileName.nMaxFile = sizeof (szFile);

OpenFileName.lpstrFileTitle = NULL;

OpenFileName.nMaxFileTitle = 0;

OpenFileName.lpstrInitialDir = NULL;

OpenFileName.lpstrTitle = "Open a File";

OpenFileName.nFileOffset = 0;

OpenFileName.nFileExtension = 0;

OpenFileName.lpstrDefExt = NULL;

OpenFileName.lCustData = NULL;

OpenFileName.lpfnHook = ComDlg32DlgProc;

OpenFileName.lpTemplateName = MAKEINTRESOURCE (IDD_COMDLG32);

OpenFileName.Flags = OFN_SHOWHELP | OFN_EXPLORER |

OFN_ENABLEHOOK | OFN_ENABLETEMPLATE;



// Call the common dialog function.

if (GetOpenFileName (&OpenFileName))

{

§

}

else

{

ProcessCDError (CommDlgExtendedError (), hWnd);

return FALSE;

}

If the user enters a filename that contains more than 12 characters, the Open common dialog procedure returns an error of FNERR_BUFFERTOOSMALL, saving you from a nasty trap. But the buffer size is not the only problem. If you are doing your own file parsing, and if you accept only the first 12 characters in a filename, you could open the wrong file. For instance, imagine that a user enters the filename Marketing Report and that the current directory contains files named Marketing Report and Marketing Salaries. If your application accepts only the first 8 characters of a filename and assumes an extension, which file will the application open?