C / C++ / MFC

Problems with Htmlhelp API library

16-Mar-03 9:26

for ( int i = 0 ; i < m_cmb.GetCount() ; ++i )
{
CString sText;
m_cmb.GetText( i, sText );
int nIndex = sText.Find( _T("ABC") );
if ( nIndex >= 0 )
{
// Found it - do something
break;
}
}

Dave

trimtrom16-Mar-03 9:00

trimtrom

16-Mar-03 9:00

Hello,

I have just been writing an application in VC++.Net Standard on Windows XP Professional, and have decided to use the latest version of HtmlHelp for the help facility. I have just installed HtmlHelp, and according to the instructions I have put htmlhelp.lib under
"C:\Program Files\Microsoft Visual Studio .NET\Vc7\lib" directory, and htmlhelp.h under the similarly named include directory.

I have written the following API code to invoke the Help system:

void CMainFrame::OnCallHlp()
{
::HtmlHelp((HWND)GetDesktopWindow(),
"C:\\C++Proj\\LPSEmail\\LPShlp\\html\\LPSEmail.chm::
/afxFoldersAdd.htm", HH_DISPLAY_TOPIC,NULL);
}

However, when I compile I get the following link error:

LPSEmail error LNK2019: unresolved external symbol _HtmlHelpA@16 referenced in function "public: void __thiscall CMainFrame::OnCallHlp(void)" (?OnCallHlp@CMainFrame@@QAEXXZ)

I would be very grateful if someone could tell me how to make the programme link correctly. I presume the problem is because it cannot find the external HtmlHelp API library??

All help appreciated,

Trimtrom

brandon187916-Mar-03 9:07

brandon1879

16-Mar-03 9:07

You may need to link with a dll. I don't know the HTMLHelp API, but unless it comes standard in .NET, it might be good to check that. Also, are you sure that it's not under some namespace. With a different API like that, it could be a namespace different than std::.

trimtrom16-Mar-03 9:15

trimtrom

16-Mar-03 9:15

Brandon,
Thanks for the answer. In the SDK docs there is no mention of a DLL.

I am not very experienced and so would not know how to check for a namespace. How would you do that??

Would it help if I deleted the pch files under the Debug directory, if there is some inherited problem?

Neville Franks16-Mar-03 9:13

16-Mar-03 9:13

You need to include HtmlHelp.lib in your Link|Library modules project setting.

Neville Franks, Author of ED for Windows. www.getsoft.com
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trimtrom16-Mar-03 9:26

trimtrom

16-Mar-03 9:26

Neville,
I have been looking under Tools, Options, Project folder. (This is very different to VC++ 6 which I was used to.)

Is there any where else I should check?

Trimtrom

Neville Franks16-Mar-03 9:30

16-Mar-03 9:30

I don't have VC7 so I can't help with that. Gotta be there somewhere. Linker Options should be part of the project setup. At least that's how it is in VC6.

Neville Franks, Author of ED for Windows. www.getsoft.com
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PJ Arends16-Mar-03 14:46

PJ Arends

16-Mar-03 14:46

Project menu -> Properties -> Linker -> Input -> Additional Dependencies.

easier way is to use a #pragma preprocessor directive

#pragma comment (lib, "htmlhelp.lib")

Sonork 100.11743 Chicken Little

"You're obviously a superstar." - Christian Graus about me - 12 Feb '03

Within you lies the power for good - Use it!

Dave Bryant16-Mar-03 9:13

16-Mar-03 9:13

You need to link with htmlhelp.lib which is provided with the Microsoft HTML Help Workshop.

Dave

Neville Franks16-Mar-03 9:20

16-Mar-03 9:20

Are you following me around. Big Grin | :-D

Neville Franks, Author of ED for Windows. www.getsoft.com
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Dave Bryant16-Mar-03 9:22

16-Mar-03 9:22

I got there first on the previous one Poke tongue | ;-P

Dave

Interdependent classes

brandon187916-Mar-03 8:54

brandon1879

16-Mar-03 8:54

I have a project that I need to have a class A with a member pointer to a class B; class B has a member pointer to class A. How do I mess with the header files are whatever to do this?

I would also like to know how most people do their header files #includes. Is it like MS with one header file including every other header file and every source file includes that with #ifndef and #endif around every header file? Sorry, that sounds confusing. One main header file that #include's every header file, classes and such. Then every header file with a class declaration has #ifndef, #endif around it so it won't include more than once. Lastly, all source files only #include the main header file, nothing else. If this is the best way to do it, does it matter to #include one header file before another?

Coming back to my original question, I'm sure you can do preprocessor directives like console function declarations with classes. But where would I put those?

Anonymous16-Mar-03 9:16

Anonymous

16-Mar-03 9:16

You need a forward declaration of one of the classes that tells the compiler that the class exists, but you'll define it later:

class A;

class B
{
private:
A *m_Ptr;
};

It is wise to always put a #ifdef round every header file, but personally I would only include a header file where you need - needlessly including every single header file will just create a big spaghetti mess. Keep it clean and include as much as you can in the source files, and whatever is needed in the header file to compile the class. Otherwise as soon as you start changing one header everything falls apart

Dave Bryant16-Mar-03 9:17

16-Mar-03 9:17

class1.h

#if !defined(__CLASS1_H__)
#define __CLASS1_H__

// Forward declaration
class Class2;

class Class1
{
Class2* m_pClass2;

// Other stuff
};

#endif

class2.h

#if !defined(__CLASS2_H__)
#define __CLASS2_H__

// Forward declaration
class Class1;

class Class2
{
Class1* m_pClass1;

// Other stuff
};

#endif

Then include both of the header files in the implementation of these classes.

Dave

Neville Franks16-Mar-03 9:19

16-Mar-03 9:19

brandon1879 wrote:
I have a project that I need to have a class A with a member pointer to a class B; class B has a member pointer to class A. How do I mess with the header files are whatever to do this?

You need to forward declare class b. eg.

class b;

class a { ... class b* m_b; }
class b { ... class a* m_a; }

For a good discussion on #includes I recomend "Large Scale C++ Software Design" by John Lakos. published by Addison-Wesley.

Bottom line is that you should only include the minimum number of #includes that you need. Using a #include that #includes a set of include files is a bad idea. You need to minimimize dependencies so files aren't recompiled unnecessarily.

Neville Franks, Author of ED for Windows. www.getsoft.com
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