CWinApp::m_pszHelpFilePath
Remarks
Contains the path to the application’s Help file. By default, the framework initializes m_pszHelpFilePath to the name of the application with ".HLP" appended. To change the name of the help file, set m_pszHelpFilePath to point to a string that contains the complete name of the desired help file. A convenient place to do this is in the application's InitInstance function. m_pszHelpFilePath is a public variable of type const char*.
Note If you assign a value to m_pszHelpFilePath, it must be dynamically allocated on the heap. The CWinApp destructor calls free( ) with this pointer. You many want to use the _tcsdup( ) run-time library function to do the allocating. Also, free the memory associated with the current pointer before assigning a new value. For example:
//First free the string allocated by MFC at CWinApp startup.
//The string is allocated before InitInstance is called.
free((void*)m_pszHelpFilePath);
//Change the name of the .HLP file.
//The CWinApp destructor will free the memory.
m_pszHelpFilePath=_tcsdup(_T(“d:\\somedir\\myhelp.hlp”));