Can Anybody Know what is the problem with this code (using HTMLHelp API function)?

The problem is that you do not check whether 'LoadLibrary()' suceeds and 'GetProcAddress()' returns a valid pointer:

void OnHelp()
{
    HINSTANCE inst = LoadLibrary("HHCTRL.OCX");

    if ( NULL == inst) {

    // error
    }
   
    FARPROC htmlHelp = GetProcAddress(inst,
                                     "HtmlHelp");

    if ( NULL == htmlHelp) {

    // error
    }

    HWND g = htmlHelp(m_hWnd,                          "C:\\MyHelp.chm",                          2,
NULL);
    FreeLibrary(inst);

}

No, I have debug the code and the Loadlibrary function executed successfuly, the problem found in htmlHelp function itself, specialy the third parameter I have passed value 2 without knowing what is the exactly value?

In the file HTMLHELP.H, you will see:

#define HH_DISPLAY_INDEX        0x0002  // not currently implemented

so you ar passing in a request for an 'unimplemented command'.  However, another reference indicates that this is an avaialbel command.  If used, you need to pass in a keyword to lookup

Typcial usage is to use (e.g.):

#include <htmlhelp.h>

HWND g = htmlHelp(
        m_hWnd,
        "C:\\MyHelp.chm",
        HH_DISPLAY_TOPIC, // 0
        NULL
);

To lookup a keyword, try:

HWND g = htmlHelp(
        m_hWnd,
        "C:\\MyHelp.chm",
        HH_DISPLAY_INDEX,  // 2
        (DWORD)"Frabisculate"
);


There is extensive on-line infoemation on how to use the HtmlHelp API here:

http://search.microsoft.com/gomsuri.asp?n=1&c=rp_Results&siteid=us/dev&target=http://msdn.microsoft.com/library/en-us/htmlhelp/html/vsconHH1Start.asp

-- Dan

Unfortunitly my machine can not find <htmlhelp.h> file,where can I find this file