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I am integrating context specific help for my MFC winforms application. Calling following function crashes my application and hhctrl.ocx is the culprit as per crash log. I think the problem is with 64bit version of hhctrl.ocx in System32 bit folder since my application works fine in 32 bit mode. I tried registering both 32bit and 64bit ocx but that didn't help.

//added following line in InitInstance of application
DWORD m_dwCookie;
HtmlHelp(NULL, NULL, HH_INITIALIZE,(DWORD)&m_dwCookie);

I know this is very very old API for html help integration. Is there an alternate framework for helpfile integration into MFC application if I can't get around the issue?

Adrian Mole
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Patel
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  • Does is crash on all computers or nly on your developement computer? – Jabberwocky Apr 16 '20 at 06:13
  • Thanks for reply. I've only tested it on development environment. I'll try it on different OS. I actually sent a support request to MSDN and someone commented that Issue seems to be with windows 10 SDK and I'll have to contact the other team. By the way, I wrote C# wrapper to call Help.ShowHelp() functions and calling them from C++/CLI. That seems to work fine but It does not have a method of retrieving help description from Popup from chm. Basically, I'll have to pass my description to wrapper since it can't grab it from .chm. – Patel Apr 16 '20 at 13:24
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    Also try in release mode without the debugger. If you find out anything, post an answer or comment here. – Jabberwocky Apr 16 '20 at 13:26
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    I forgot to mention that I had a C++ class that wraps calls around HTMLHelp() functions. I was creating an instance of that class by declaring it as a member variable in CWinApp derived class. I was able to solve crashing issue by creating instance of that wrapper class using "new" in InitInstance. So, basically, I had to delay the object creation. However, I run into a different issue now where none of my call (e.g. CMDIChildWnd::OnCommandHelp) from child frame cause CMDIFrameWnd::WinHelp() to be called. Same Code works in 32 bit though. I may end up calling for WinHelp() directly instead. – Patel Apr 16 '20 at 20:44
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    It turned out to be my fault. I had to use HtmlHelp instead of WinHelp. – Patel Apr 18 '20 at 20:15

1 Answers1

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There is a problem in your code, in the last parameter of the HtmlHelp call. You cast this to a DWORD value, which you shouldn't. This will work on 32-bit systems, where a pointer (address) is a 32-bit value but, on 64-bit platforms/builds, a pointer is 64-bits, so your cast to DWORD will wipe out the upper 32-bits, leaving an invalid address when it is then (automatically) 're-promoted' to a 64-bit value.

What you need to use is the DWORD_PTR type, instead (the size of which will vary between platforms, 32- or 64-bits, as required):

DWORD m_dwCookie;
HtmlHelp(NULL, NULL, HH_INITIALIZE, (DWORD_PTR)&m_dwCookie); // DWORD_PTR != DWORD
Adrian Mole
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