Need help with IID_IHTMLElement

You should do a test to see if pdisp is Null.
Example:
pElements->item (varName, varIndex, &pdisp);
if (pdisp == NULL)
{
//report error here, and back out
}
   SysFreeString (varName.bstrVal);
//fails here
   pdisp->QueryInterface (IID_IHTMLElement, (LPVOID *) &pItem);

Every time you do a QueryInterface(IDD_???,(LPVOID*) &pSomeVar),
you should check to see if the variable (pSomeVar) is NULL.

I'm sorry i took an unfiltered code. I have done some fixes and it should work now. I don't se any variables that is NULL after a function call. Please test this code and help me find the error.



#include <windows.h>
#include <mshtml.h>
#include <exdisp.h>

int main (void)
{
   CLSID clsid;
   LPUNKNOWN punk=NULL;
   IWebBrowser2 *pWB;
   IHTMLDocument2 *pHTML;
   IHTMLElementCollection *pElement;
   IHTMLElement *pItem;
   IDispatch *pdisp;
   DISPID dispid, dispidNamed = DISPID_PROPERTYPUT;
   DISPPARAMS dispparams;
   UINT uArgErr;
   VARIANTARG vArg;
   VARIANT_BOOL bBusy;
   VARIANT varName, varIndex, var;
   BSTR bstr;

   OleInitialize (NULL);
   CLSIDFromProgID (OLESTR("InternetExplorer.Application"), &clsid);
   CoCreateInstance (clsid, NULL, CLSCTX_SERVER, IID_IUnknown,
                     (LPVOID *) &punk);
   punk->QueryInterface (IID_IWebBrowser2, (LPVOID *) &pWB);
   punk->Release();
   pWB->put_Visible (TRUE);
   BSTR bstrVal = SysAllocString (L"C:\\TEMP\\DHTML.HTM");
   var.vt = VT_I4;
   var.lVal = 0;
   pWB->Navigate (bstrVal, &var, &var, &var, &var);
   SysFreeString (bstrVal);
   do
   {
       Sleep (500);
       pWB->get_Busy (&bBusy);
   }
   while (bBusy);
   pWB->get_Document (&pdisp);
   if (pdisp == NULL)
{
return 0;
}

   pWB->Release();
   pdisp->QueryInterface (IID_IHTMLDocument2, (LPVOID *) &pHTML);
   pdisp->Release();
   pHTML->get_all (&pElement);
   varName.vt = VT_BSTR;
   varName.bstrVal = SysAllocString (L"mytitle");
   varIndex.vt = VT_I4;
   varIndex.lVal = 0;
   pElement->item (varName, varIndex, &pdisp);
   SysFreeString (varName.bstrVal);
//fails here
   pdisp->QueryInterface (IID_IHTMLElement, (LPVOID *) &pItem);
   pdisp->Release();
   bstr = SysAllocString (L"Hello from C++!");
   pItem->put_innerText (bstr);
   SysFreeString (bstr);
   pItem->Release();
   OleUninitialize ();
}



Cheers
Andla

I run the debugger but i will put up the null checker routines laiter. To bad there are not much source code on this. :-(

/Andla

seems to be interesting code...
let's see
before the exception occurs, the pdisp is NULL

pdisp is NULL after this Line:

  pElement->item (varName, varIndex, &pdisp);

so, somthing has to be wrong here

I think the mytitle is missing but i don't know how to make a reverse enginering on this. ?


 varName.vt = VT_BSTR;
  varName.bstrVal = SysAllocString (L"mytitle");
  varIndex.vt = VT_I4;
  varIndex.lVal = 0;


/Andla

Exactly what are you trying to do with this code?
I might be able to help you get to the end result if I know what you want out of it.

#include <windows.h>
#include <mshtml.h>
#include <exdisp.h>

#pragma warning(disable:4786)
#include <vector>
#include <string>

int function1 (void)
{
     CLSID clsid;
     LPUNKNOWN punk=NULL;
     IWebBrowser2 *pWB = NULL;
     IHTMLDocument2 *pHTML = NULL;
     IHTMLElementCollection *pElement = NULL;
     IDispatch *pdisp = NULL;
     DISPID  dispidNamed = DISPID_PROPERTYPUT;
     VARIANT_BOOL bBusy;
     VARIANT varName, varIndex, var;
     BSTR bstr;

     OleInitialize (NULL);
     CLSIDFromProgID (OLESTR("InternetExplorer.Application"), &clsid);
     CoCreateInstance (clsid, NULL, CLSCTX_SERVER, IID_IUnknown, (LPVOID *) &punk);
     punk->QueryInterface (IID_IWebBrowser2, (LPVOID *) &pWB);
     punk->Release();
     pWB->put_Visible (TRUE);
     BSTR bstrVal = SysAllocString (L"www.axter.com");
     var.vt = VT_I4;
     var.lVal = 0;
     pWB->Navigate (bstrVal, &var, &var, &var, &var);
     SysFreeString (bstrVal);
     do
     {
       Sleep (500);
       pWB->get_Busy (&bBusy);
     }
     while (bBusy);
     pWB->get_Document (&pdisp);
     if (pdisp == NULL)
     {//Report error here
          return 0;
     }

     pWB->Release();
     pdisp->QueryInterface (IID_IHTMLDocument2, (LPVOID *) &pHTML);
     pdisp->Release();
     pHTML->get_all (&pElement);
     long NumItems = 0;
     pElement->get_length(&NumItems);
     if (!NumItems)
     {//Report error here
          return 0;
     }
     std::vector<std::string> ListOfTagNames;
     std::vector<std::string> ListOfInnerHTML;
     std::vector<std::string> ListOfOuterHTML;
     for (int item_number_index = 0;item_number_index < NumItems;item_number_index++)
     {
          varName.vt = VT_I4;
          //varName.bstrVal = SysAllocString (L"A Valid Name");//Only use this if you know the name of the object
          varName.lVal = item_number_index;//Get item via index number (zero based number)
          varIndex.vt = VT_I4;
          varIndex.lVal = 1;
          IDispatch *pdisp2 = NULL;
          if (pElement->item (varName, varIndex, &pdisp2) != S_OK)
          {//Report error here
               return 0;
          }
          if (pdisp2 == NULL)
          {//Report error here
               return 0;
          }
          //SysFreeString (varName.bstrVal);//Only use this if used above
          IHTMLElement *pItem = NULL;
          pdisp2->QueryInterface (IID_IHTMLElement, (LPVOID *) &pItem);
          pdisp2->Release();
          if (pItem == NULL)
          {//Report error here
               return 0;
          }
          CString TempVariable;
     

          pItem->get_tagName(&bstr);
          TempVariable = bstr;
          std::string szTagName = (LPCTSTR)TempVariable;
          ListOfTagNames.push_back(szTagName);

          pItem->get_innerHTML(&bstr);
          TempVariable = bstr;
          std::string szInnerHTML = (LPCTSTR)TempVariable;
          ListOfInnerHTML.push_back(szInnerHTML);

          pItem->get_outerHTML(&bstr);
          TempVariable = bstr;
          std::string szOuterHTML = (LPCTSTR)TempVariable;
          ListOfOuterHTML.push_back(szOuterHTML);

          bstr = SysAllocString (L"Hello from C++!");
          pItem->put_innerText (bstr);
          SysFreeString (bstr);
          pItem->Release();
     }
     OleUninitialize ();
     return 1;
}

To get additional information on any IDD_??? item, just remove the IDD_ and put the rest of the text in the VC help index box.  It should list information on the item.

Example:
pdisp->QueryInterface (IID_IHTMLDocument2, (LPVOID *) &pHTML);
The above code uses IID_IHTMLDocument2.
If you want to get information on what the QueryInterface() function will return using IID_IHTMLDocument2, you can look in the VC++ help index for "IHTMLDocument2".
It'll list all the methods available for the object.

You can also get more information on the object by search the VC++ include file directory for the IDD_????

To do that, you can use the following method.

1.  Click EDIT on the main menu of Visual C++ IDE
2.  Select "FIND-IN-FILES"
3.  In the "Find What" field, enter "IID_IHTMLDocument2" (with out the quotes)
4.  Change the "In Folder" field to point to the VC++ directory.
Example: "C:\Program Files\Microsoft Visual Studio\VC98"
5.  Select the "Look In Subfolders" field so that it is set.
6.  Make sure the "In Files/File Types" field is set to the following:
 "*.c;*.cpp;*.cxx;*.tli;*.h;*.tlh;*.inl;*.rc"
7.  Click the find button.

That should list all the VC++ source code for the object.  Which will give you some insigt as to how it works.

Good luck, and let me know if you have any questions.

Hi!

I have tested your new code.
Let se if i got this right.

pElement->get_length(&NumItems);

This is the number of tags found in the webpage.
If this is the case then i don't know how it is count.
If i count my self i get more than seven.
I could figure out this myself but appreciate your help.

Nice homepage :-)
I saw that you used AolPress to create it. I like this editor to bad they don't do any upgrades.

Thanks for your help.

Cheers
Andla.

>>I saw that you used AolPress to create it. I like this
>>editor to bad they don't do any upgrades.
Yes, I like it too.  I try using other editors, but I always end up going back to AolPress.

>>This is the number of tags found in the webpage.
That's right.

>>If i count my self i get more than seven.
It's counting the tags in the FRAME page.  Did you view the frame page?

The frame page only has seven.
I'll try posting the seven tags on my next comment, but I don't know if it'll show up, because EE some times has problems displaying tags in the comment block.

I'm wrong, and you're right.  It does have more then seven tags.

HTML
HEAD
TITLE
!--
FRAMESET COLS
FRAME SRC=
FRAME SRC=

NOFRAMES
BODY
P

The last three tags were not counted (NOFRAMES, BODY, P).

I believe the last three tags were not counted because they're only used for a No-Frame browser.

Ok Axter you have been very helpful.

BTW about the Aolpress i discovered that if you copy an image on the screen 'Ctrl+C' and paste it in AolPress 'Ctrl+V' it will automatically paste the bitmap image in AolPress and convert it to jpeg and you don't even have to name them. If you create a tutorial with screen shots you can do this in notime. I use irfanview to take screen shots every second and save it to a folder.

Cheers
Andla