C / C++ / MFC

Re: Detect USB Pendrive [modified]

David Crow21-Sep-09 4:01

David Crow

21-Sep-09 4:01

Have you looked at the WM_DEVICECHANGE message?

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

Iain Clarke, Warrior Programmer21-Sep-09 6:07

Iain Clarke, Warrior Programmer

21-Sep-09 6:07

Follow my name, to my articles. One of them should do exactly what you want.

Iain.

[modified:] ps, OK, I'll help you be lazy:
Detecting when drives are added or removed[^]

I have now moved to Sweden for love (awwww).
If you're in Scandinavia and want an MVP on the payroll (or happy with a remote worker), or need cotract work done, give me a job! http://cv.imcsoft.co.uk/[^]

modified on Monday, September 21, 2009 12:31 PM

Rajesh R Subramanian21-Sep-09 9:02

21-Sep-09 9:02

Iain Clarke, Warrior Programmer wrote:
Follow my name, to my articles. One of them should do exactly what you want.

Iain Clarke, Lazy Programmer. Smile | :)

It is a crappy thing, but it's life -^ Carlo Pallini

Iain Clarke, Warrior Programmer

Iain Clarke, Warrior Programmer21-Sep-09 9:16

21-Sep-09 9:16

Well, the article is pretty well titled, in an appropriately named section.
So my initial thought was that is they could not even be bothered to follow my instructions, they can do without help!

As you can see, I weakened!

Iain Clarke, Softie Programmer!

Moak24-Sep-09 5:01

Moak

24-Sep-09 5:01

Thanks, good to know! Smile | :)

/Lazy Moak

Webchat in Europe Java | [Coffee]

(only 4K)

Thread pool query

Rajesh R Subramanian21-Sep-09 3:14

21-Sep-09 3:14

I am using the original thread pool API provided by Windows (Not the latest one present in Vista and above) and I use QueueUserWorkItem[^] to submit new work to the queue.

After the threads start to execute and several work items are queued, is there any way with which I could find out the number of threads alive in the threadpool (including idle ones, if any)? I know that I can be monitoring this with tools like ProcessMonitor from sysinternals. But, that's not what I want. I'm not able to find something like GetThreadCount() the thread pool API.

I do understand that there is no need for me to know this, because the thread pool API guarantees to take care of dynamically creating or destroying threads depending on the work load and other criteria. However, I'm just curious. Smile | :)

Many thanks.

It is a crappy thing, but it's life -^ Carlo Pallini

Naveen21-Sep-09 4:04

Naveen

21-Sep-09 4:04

Rajesh R Subramanian wrote:
I was I'm not able to find something like GetThreadCount() the thread pool API.

The CreateToolhelp32Snapshot() function with TH32CS_SNAPTHREAD might be helpful. isnt it?

DWORD GetThreadCount()
{
    THREADENTRY32 stThreadEntry = {0};
    stThreadEntry.dwSize = sizeof( stThreadEntry );
    HANDLE hSnap = CreateToolhelp32Snapshot( TH32CS_SNAPTHREAD, 0 );
    if( !Thread32First( hSnap, &stThreadEntry ))
    {
        return 0;
    }
    int nCount = 0;
    DWORD dwCurrentProcessId = GetCurrentProcessId();
    do 
    {
        if( dwCurrentProcessId == stThreadEntry.th32OwnerProcessID )
        {
            nCount ++;
        }
    } while (Thread32Next(hSnap, &stThreadEntry ));
    return nCount;
}

nave

[OpenedFileFinder] [My Blog]

Rajesh R Subramanian21-Sep-09 4:42

21-Sep-09 4:42

Hi Naveen,

Just wanted to quickly say thanks. I don't have VS installed, so I'll have to get back to the development machine to try it. On the other hand, it looks like this is going to return me the number of threads that my application is running. I'll be in a bit of yogurt in that case. I say it because there are threads started and being run from other modules as well (outside of the thread pool code, but within the app) and I want to be able to find the number of threads that specifically belong to the pool. I think I'll need to put in a bit more research.

But this is definitely a good start. Thanks again. Smile | :)

It is a crappy thing, but it's life -^ Carlo Pallini

Naveen21-Sep-09 7:10

Naveen

21-Sep-09 7:10

Hi Rajesh,

Rajesh R Subramanian wrote:
On the other hand, it looks like this is going to return me the number of threads that my application is running

ya. I thought if the module is small, you know the count of other threads. BTW where is the option to find out the thread pool's thread count in process explorer?

Rajesh R Subramanian wrote:
I want to be able to find the number of threads that specifically belong to the pool. I think I'll need to put in a bit more research.

It's bit interesting. May be by checking the thread entry point we can decided whether the thread belongs to thread pool. How ever I don't know any direct method which returns the thread entry point. Stack walking may not work always if proper pdb files are not available. isnt it?

Any way if you come up with a method I would like to hear about it. Best wishes...

nave

[OpenedFileFinder] [My Blog]

Rajesh R Subramanian21-Sep-09 7:48

Cell change event in Excel

21-Sep-09 7:48

Naveen wrote:
ya. I thought if the module is small, you know the count of other threads.

No, this is a fairly large project (even though the module that uses thread pools is relatively small). But of course yes, I can do my little test with a smaller dummy project. Smile | :)

Naveen wrote:
BTW where is the option to find out the thread pool's thread count in process explorer?

There's no direct option as such, but the no. of threads that we create manually (as opposed to being managed by a pool managing algorithm driven by the OS), we have a count of it. Add 1 to it (the application's main thread). Now, we can subtract this number from the number of threads shown by process explorer for our process.

I was thinking of exploiting two things as well:

1. Entry point of the thread (like you said)
2. Do some experimenting with TLS (TLS won't work "properly" with pools, because any thread might execute the thread code, but TLS is guaranteed to be unique for a given thread).

I'll notify you if I post a reply here. But, I need to get some sleep now. I've had a long day. Smile | :)

It is a crappy thing, but it's life -^ Carlo Pallini

NarVish21-Sep-09 0:35

21-Sep-09 0:35

Hi,
I'm new to VC++. In C#, I used the event "DocEvents_ChangeEventHandler", to handle the cell changes in Excel file. Please guide me to handle the same in VC++.
Thanks in advance.

Stuart Dootson21-Sep-09 2:35

21-Sep-09 2:35

Here's a complete example that fires up Excel and handles some application events - the general principle (registering an object with Excel to handle its events) will be exactly the same for document events, except you'll register the handler with the relevant workbook, I guess and have to change the event handler object to suit the DocEvents as opposed to AppEvents. As you're new to C++, I'd advise you get a little more familiar with C++ (and the Microsoft specific bits of VC++) before diving into this too deeply.

#include <atlbase.h>
#include <atlcom.h>
// Reference the Excel object model
#import "libid:00020813-0000-0000-C000-000000000046" auto_search no_dual_interfaces rename("DialogBox", "excelDialogBox") rename("RGB", "excelRGB") rename("DocumentProperties", "excelDocumentProperties") rename("SearchPath", "excelSearchPath") rename("CopyFile", "excelCopyFile") rename("ReplaceText", "excelReplaceText")

// Define the AppEvents handler object.

// First define fucntion information for the events we want to handle
_ATL_FUNC_INFO SheetChangeInfo = { CC_CDECL, VT_EMPTY, 2, { VT_DISPATCH, VT_DISPATCH } };
_ATL_FUNC_INFO AfterCalculateInfo = { CC_CDECL, VT_EMPTY, 0, { } };

// And define an event handler object - note that this object just sets a boolean
// variable to true when a handled event is seen
class ExcelAppEventHandler : public IDispEventSimpleImpl<1, ExcelAppEventHandler, &__uuidof(Excel::AppEvents)>
{
public:
   ExcelAppEventHandler(bool& doneFlag) : done_(doneFlag) { done_ = false; }
   // The sink map maps event handler functions to the events they handle
   BEGIN_SINK_MAP(ExcelAppEventHandler)
      SINK_ENTRY_INFO(1, __uuidof(Excel::AppEvents), 0x0000061c, &ExcelAppEventHandler::SheetChange, &SheetChangeInfo)
      SINK_ENTRY_INFO(1, __uuidof(Excel::AppEvents), 0x00000a34, &ExcelAppEventHandler::AfterCalculate, &AfterCalculateInfo)
   END_SINK_MAP()

   // Event handling methods. These match the signatures given in the AppEvents
   // definition except for the return type and we've added in the _stdcall
   // calling convention.
   void _stdcall SheetChange(IDispatch *, struct Excel::Range *)
   {
      done_ = true;
   }
   void _stdcall AfterCalculate()
   {
      done_ = true;
   }
private:
   bool& done_;
};

int _tmain(int argc, _TCHAR* argv[])
{
   // Tell the system we're using COM
   CoInitializeEx(0, COINIT_MULTITHREADED);
   {
      //Declare an Excel object pointer
      Excel::_ApplicationPtr xl;
      // And get a reference to the currently running instance of Excel
      if (SUCCEEDED(xl.GetActiveObject(__uuidof(Excel::Application))))
      {
         // Make sure there's at least one workbook
         xl->Workbooks->Add();
         bool done = false;

         // Instantiate the event handler
         ExcelAppEventHandler handler(done);
         // Tell Excel about the handler
         if (SUCCEEDED(handler.DispEventAdvise(xl)))
         {
            // Run a Windows message loop to pump COM messages - this is needed
            // because that's how COM works...
            MSG msg;
            while (!done && GetMessage(&msg, NULL, 0, 0) > 0) {
               TranslateMessage(&msg);
               DispatchMessage(&msg);
            }            
            // Tell Excel we don't want to handle events any more.
            handler.DispEventUnadvise(xl);
         }
      }
   }
   // Tell the system we're done with COM
   CoUninitialize();
   return 0;
}

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

NarVish21-Sep-09 20:31

21-Sep-09 20:31

Thank you so much. Your reply is very helpful.

NarVish23-Sep-09 23:26

23-Sep-09 23:26

I've added the following code in SheetChange function, to retrieve the data entered in excel cells.
void _stdcall SheetChange(IDispatch *, struct Excel::Range *target)
{
_bstr_t result= target->GetAddress(1,1,Excel::XlReferenceStyle::xlR1C1,1,1);
string str=result;

std::cout << "str is: " << str << "\n";
int index1 = str.find("!R");
int index2 = str.find("C");

string rowIndex = str.substr(index1+2);
string colIndex = str.substr(index2+1);
rowIndex = str.substr(index1+2);
colIndex = str.substr(index2+1);

int rIndex = atoi(rowIndex.c_str());
int cIndex = atoi(colIndex.c_str());

Excel::RangePtr rangePtr = target->Worksheet->Cells;
_variant_t vItem = rangePtr->Item[rIndex][cIndex];
_bstr_t bstrText( vItem );

cout << bstrText;
}

bstrText contains data in excel cell. where as its not retrieving the automatic changes.
for example, C1 cell contains the function =SUM(A1,B1), A1 = 10, B1=20 then C1=30

if I changed value in A1 to 15, at a time there will changes in two cell, i.e, A1(15) and C1(35).
I'm able to get the A1 value but not C1. How can I trace C1 value (automatic changes).
Please guide me to solve this.
Thanks in advance.

Stuart Dootson24-Sep-09 5:57

24-Sep-09 5:57

Has C1 actually changed? I would say not. It's formula has stayed the same. The documentation says that the SheetChange event is fired when a cell is changed by the user - you only change 1 cell, which is A1.

To catch when cells are recalculated, there's a Calculate event.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

NarVish24-Sep-09 19:32

24-Sep-09 19:32

C1 is getting changed as soon as A1 or B1 gets changed.
To catch when cells are recalculated, I added SheetCalculate event as below

_ATL_FUNC_INFO SheetCalculateInfo = { CC_CDECL, VT_EMPTY, 0, { VT_DISPATCH, VT_DISPATCH } };

SINK_ENTRY_INFO(1, __uuidof(Excel::AppEvents), 0x00000a34, &ExcelAppEventHandler::SheetCalculate, &SheetCalculateInfo)

void _stdcall SheetCalculate(IDispatch *iDispatch)
{
cout << "Inside SheetCalculate" ;
}

When I changed function related cells, SheetCalculate function is not getting fired.
I think declaration of _ATL_FUNC_INFO SheetCalculateInfo is incorrect.
Please correct me to fire SheetCalculate function, to read the automatic cell changes.

Stuart Dootson24-Sep-09 20:11

24-Sep-09 20:11

SheetCalculate is a WorkBook event. You've put the SheetCalculate event signature in an Application event handler, judging by the mention of AppEvent all over the code. You would need a separate WorkBook event handler that you register (with DispEventAdvise) with the workbook you're interested in.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

NarVish24-Sep-09 21:26

24-Sep-09 21:26

Thank you for your support. Can you give sample code around this.
and also it would be great if you can point me to complete documentation on interfacing Excel

Stuart Dootson25-Sep-09 4:03

25-Sep-09 4:03

Workbook SheetCalculate event handler:

_ATL_FUNC_INFO SheetCalculateInfo = { CC_CDECL, VT_EMPTY, 1, { VT_DISPATCH } };

class ExcelBookEventHandler : public IDispEventSimpleImpl<1, ExcelBookEventHandler, &__uuidof(Excel::WorkbookEvents)>
{
public:
	BEGIN_SINK_MAP(ExcelBookEventHandler)
		SINK_ENTRY_INFO(1, __uuidof(Excel::WorkbookEvents), 0x0000061b, &ExcelBookEventHandler::SheetCalculate, &SheetCalculateInfo)
	END_SINK_MAP()

	void _stdcall SheetCalculate(IDispatch *)
	{
		std::cout << "ExcelBookEventHandler::SheetCalculate\n";
	}
};

Then given I have an Excel Application interface pointer called xl, I use this to register the event handler:

 Excel::_WorkbookPtr wb = xl->Workbooks->Add();
ExcelBookEventHandler calc;
calc.DispEventAdvise(wb);

The same dispatch loop is used as I used before.

NarVish wrote:
it would be great if you can point me to complete documentation on interfacing Excel

Not sure there IS any. The Excel help available through the VBA IDE tells you all about the Excel object model, and that's all you really need to know, except for some details (like dispids, etc) that I get by opening the Excel type library with the OLE/COM Object Viewer.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

NarVish29-Sep-09 19:45

29-Sep-09 19:45

Thank you for your post.
SheetCalculate is getting fired whenever there is change in function related cells. My aim is to get the function result in excel. To get that I'm trying by calling different functions of iDispatch. But couldn't able to get the expected result.

void _stdcall SheetCalculate(IDispatch *iDispatch)
{
////////////*******GetIDsOfNames*******////////////
static DISPID dispid = 0;
wchar_t *ucName = L"Evaluate"; //I tried by giving "Run" and "Calculate" values in place of "Evaluate"
HRESULT result = iDispatch->GetIDsOfNames(IID_NULL, &ucName, 1,LOCALE_SYSTEM_DEFAULT, &dispid);

////////////*******Invoke*******////////////
VARIANT varResult;
DISPID dispid;
DISPID dispidNamed = DISPATCH_METHOD;
EXCEPINFO excep;
UINT uArgErr;
DISPPARAMS dispparams;
dispparams.cNamedArgs = 0;
dispparams.cArgs = 2;
dispparams.rgdispidNamedArgs = &dispidNamed;
HRESULT result = iDispatch->Invoke( odispid, IID_NULL, LOCALE_SYSTEM_DEFAULT,
DISPATCH_METHOD, &dispparams, &varResult, &excep, &uArgErr);

////////////*******GetTypeInfo*******////////////
ITypeInfo* pTypeInfo;
HRESULT result= iDispatch->GetTypeInfo(0,LOCALE_SYSTEM_DEFAULT,&pTypeInfo);

////////////*******GetTypeInfoCount*******////////////
UINT pct1;
HRESULT result= iDispatch->GetTypeInfoCount(&pct1);

////////////*******QueryInterface*******////////////
HRESULT result = iDispatch->QueryInterface(IID_IDispatch,(void**)&iDispatch);
}
I followed the below link to get some help.
"http://up.m-e-c.biz/up/books/Excel%20add-in%20C++.pdf"

NarVish30-Sep-09 18:29

30-Sep-09 18:29

Hi Stuart Dootson,
I implemented the cell change event functionality in C#.Net. Due to environmental dependencies, our project was shifted to VC++. and I'm new to C++. Please bear with me to solve the above post. A million thanks in advance...

NarVish15-Oct-09 1:38

15-Oct-09 1:38

Which event gets fired when a new Excel application is created. I handled NewWorkbook event of AppEvents. It gets triggered only when I create new excel workbook.
Please let me know which event handles the new Excel application instance.
Thanks in advance.

Stuart Dootson15-Oct-09 2:26