Re: CLR Console Application

From:
"Brian Muth" <bmuth@mvps.org>
Newsgroups:
microsoft.public.vc.atl
Date:
Tue, 12 Feb 2008 20:21:29 -0800
Message-ID:
<OiqUKhfbIHA.3972@TK2MSFTNGP03.phx.gbl>
"Arunesh" <Arunesh@discussions.microsoft.com> wrote in message news:4F0E12C0-2697-41DF-8BE8-03A9684F23F4@microsoft.com...

Hello:

I have created a CLR console application in visual Studio 2005. I am trying
invoke an ASP file and save it locally. Please find code.

CString csFileName;
CLSIDFromProgID (OLESTR("InternetExplorer.Application"), &clsid);
CoCreateInstance (clsid, NULL, CLSCTX_SERVER, IID_IUnknown, (LPVOID *)
&punk);
punk->QueryInterface (IID_IWebBrowser2, (LPVOID *) &pWB);
punk->Release();
CString csFile;
CString InvId = _T("343");
csFile.Format(_T("http://Localhost/IMyfile/IMyfile.asp?InvId=%s"),InvId);
bstrVal = csFile.AllocSysString();
var.vt = VT_I4;
var.lVal = 0;
pWB->Navigate (bstrVal, &var, &var, &var, &var);
SysFreeString (bstrVal);
LPDISPATCH lpDispatch = NULL;
hr = pWB->get_Document(&lpDispatch);
if (SUCCEEDED(hr))
{

hr = lpDispatch->QueryInterface(IID_IPersistFile, (void **)&pFile);
if SUCCEEDED(hr)
{
  if (pFile->Save(csFileName,0)==E_FAIL)
Console::WriteLine(L"Unable to SaveComplete File");
else
hr = pFile->SaveCompleted(csFileName);
}
else
{
Console::WriteLine(L"Error in creating the Query Interface");
}

}
Console::WriteLine(L"able to SaveComplete File");
pFile->Release();
lpDispatch->Release();
               pWB->Quit();

I have inlcuded required header files(#include <exdisp.h>,#include <mshtml.h>,
#include <atlstr.h> and #include <atltime.h>) This code works fine if debug
it step by step but If I run it whether exe in debug mode or release mode, it
throws an error that System.NullReferenceException was unhandled. It points
to code pFile->Release();
lpDispatch->Release();

Please let me know what i am doing wrong.

Thanks in advance


For one thing, I see that if your second QueryInterface fails, you print out "able to Save Complete File" (which is a lie) and then
you free an interface pointer that was never assigned (pFile). Whether or not this is your issue, I don't know. Also, you need to be
checking more HRESULT's to harden up this code. You don't check the HRESULT of the CoCreateInstance, nor the first QueryInterface.
If the latter fails, your program will die when it tries to use pWB.

Brian

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