C / C++ / MFC

18-Mar-08 16:28

Yes. As long as nobody takes control of the primary buffer,
all secondary DirectSound buffers should be mixed by the
system.

Works fine on XP and Vista I know for sure.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Opaque COleClientItem

Kyudos18-Mar-08 13:30

Kyudos

18-Mar-08 13:30

I want my COleClientItem derived items to draw with the DVASPECT_OPAQUE flag but COleClientItem::Draw doesn't support the DVASPECT2 enumeration.

I think I need to check if my COleClientItem supports IViewObject2 and then call IViewObject2::Draw, but I don't really know how to go about it.

Can anyone help me?

Is this even the correct method?

Cheers

Converting int to string

J_E_D_I18-Mar-08 9:19

J_E_D_I

18-Mar-08 9:19

I have two questions. The first one is regarding the conversion from int to string. I can successfully convert a numeric string to int with the follwing code (particularly useful if you need to make mathematical operations on the numeric values contained in a string):

string VALUE_AS_STRING = "1234";
int VALUE_AS_INT = atof (VALUE_AS_STRING.c_str());
cout << "The numeric value of the string is: " << VALUE_AS_INT;

...but I am not able to do the opposite, eg convert an int into a string. Any help please?

Second question :
How come the condition below results in an error? How should it rather be written?

char CHARACTER = "1";
if (CHARACTER == "1") {cout << "True";}

Many thanks

Maxwell Chen18-Mar-08 9:27

18-Mar-08 9:27

J_E_D_I wrote:
int VALUE_AS_INT = atof (VALUE_AS_STRING.c_str());

Should use atoi().

J_E_D_I wrote:
I am not able to do the opposite, eg convert an int into a string.

sprintf()

J_E_D_I wrote:
char CHARACTER = "1";
if (CHARACTER == "1") {cout << "True";}

Use single quote.

if(character == 'a') {
  cout << "It is a";
}

Maxwell Chen

Mark Salsbery18-Mar-08 9:41

18-Mar-08 9:41

J_E_D_I wrote:
but I am not able to do the opposite, eg convert an int into a string. Any help please?

Another method in addition to Maxwell's sprintf()...

#include <sstream>
...
int SomeInt = 5;

std::ostringstream NumericStringStream;

NumericStringStream << SomeInt;

std::string NumericString = NumericStringStream.str();

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Joe Woodbury18-Mar-08 15:57

Joe Woodbury

18-Mar-08 15:57

itoa

Anyone who thinks he has a better idea of what's good for people than people do is a swine.
- P.J. O'Rourke

Is it okay to cast from int to unsigned char *?

ThatsAlok18-Mar-08 19:59

ThatsAlok

18-Mar-08 19:59

For Question One :-

would wsprintf or CString::format is of any use!

J_E_D_I wrote:
Second question :
How come the condition below results in an error? How should it rather be written?

char CHARACTER = "1";
if (CHARACTER == "1") {cout << "True";}

use ' instead of "

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
Support CRY- Child Relief and You/codeProject$$>

ChemmieBro18-Mar-08 8:54

Re: Is it okay to cast from int to unsigned char *?

18-Mar-08 8:54

I have a 32bit int that I'm trying to stuff into an array of bytes.
Is it okay to do this?

CharArray = new unsigned char [4];
CharArray = (unsigned char *)&IntegerValue
ByteArray[Length-4] = CharArray[3]
ByteArray[Length-3] = CharArray[2]
ByteArray[Length-2] = CharArray[1]
ByteArray[Length-1] = CharArray[0]

Mark Salsbery18-Mar-08 9:04

Re: Is it okay to cast from int to unsigned char *?

18-Mar-08 9:04

Yes it's ok (to cast from int * to unsigned char *).

Also is that a typo? You overwrite the allocated CharArray...
should that have been:

ByteArray = new unsigned char [Length];
CharArray = (unsigned char *)&IntegerValue

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

ChemmieBro18-Mar-08 9:20

Re: Is it okay to cast from int to unsigned char *?

18-Mar-08 9:20

No, that's not a typo.
The ByteArray is actually a different array type, but is still an array of unsigned char.

If it is okay to get the IntegerValue into the unsigned char[4] then I'm okay.

so...
CharArray = new Unsigned Char [4];
CharArray = (unsigned char*)&IntegerValue ;

That should still be fine. The 4 Unsigned Char bytes will then be populated with the bytes from the integer.

Mark Salsbery18-Mar-08 9:24

Re: Is it okay to cast from int to unsigned char *?

18-Mar-08 9:24

ChemmieBro wrote:
No, that's not a typo

In that case you have a problem Smile | :)

...

CharArray = new unsigned char [4];
CharArray = (unsigned char *)&IntegerValue //<--- overwrites the pointer allocated above!!

The storage has already been allocated - it is the 4 bytes used by the
IntegerValue variable.

You only need the second line above...

CharArray = (unsigned char *)&IntegerValue;

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

ChemmieBro18-Mar-08 9:36

Re: Is it okay to cast from int to unsigned char *?

18-Mar-08 9:36

I see that, now.
Thank you. I just needed a quick answer and got it.
I'm just re-using some code and they had done this same thing using an integer and a two shorts. I figured if it worked that way, it would work using an integer and four unsigned chars. Now I'll have to change the old stuff, too.

Thanks again.

David Crow18-Mar-08 9:33

David Crow

18-Mar-08 9:33

Have you considered using a union?

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: Is it okay to cast from int to unsigned char *?

Maxwell Chen18-Mar-08 9:36

Re: Is it okay to cast from int to unsigned char *?

18-Mar-08 9:36

DavidCrow wrote:
using a union

I like your solution!

Maxwell Chen

ChemmieBro18-Mar-08 9:38

Re: Is it okay to cast from int to unsigned char *?

18-Mar-08 9:38

No. This is existing code and I was just curious if I was allowed to do that or not. I thought I could but couldn't find anything out there to confirm that it would work correctly.
I will look up Unions, though, for future reference.
Thank you.

Maxwell Chen18-Mar-08 9:49

Re: Is it okay to cast from int to unsigned char *?

18-Mar-08 9:49

ChemmieBro wrote:
No. This is existing code

You still can use union in the existing code! And you won't even need to cast.

ChemmieBro wrote:
I thought I could but couldn't find anything out there to confirm that it would work correctly.

You have the debugger of VC++ for you to watch the memory addresses and the values.

Maxwell Chen

Mark Salsbery18-Mar-08 10:21

Re: Is it okay to cast from int to unsigned char *?

18-Mar-08 10:21

Maxwell Chen wrote:
You still can use union in the existing code!

Except for the swapping of byte order (if I read the original code correctly).

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

ramana.g18-Mar-08 17:30

ramana.g

18-Mar-08 17:30

Another way is...

int nNum = 10;
char Data[4] = {0};
memcpy(&Data, &nNum, 4);

Automation Server Questions

garyflet18-Mar-08 8:53

garyflet

18-Mar-08 8:53

I'm using VC++ 6 service pack 6 on Windows 2000. I'm working with an automation server MDI application with the following requirements.

1) Can be started by user with visible interface.
2) Only one instance at a time.
3) If controlled by client, runs in background (invisible) initially.
4) Client(s) has option to make application visible.
5) If visible and user attempts to close with client(s) connections, warning is given with choice to close or not.
6) Has menu item that allows user to disconnect from all clients.
7) If invisible, closes when last client disconnects.

I have no problem with 1-4, the questions arise with 5-7. In order to implement these, the server needs to know if there are clients connected to it. My main automation class (CAutoApp) is instantiated every time a client contacts it. In the constructor I add to a static array of LPUNKOWNs (m_lpUnk[MAXNUMCONN]) using GetInterface(&IID_IUnknown):

LPUNKNOWN CAutoApp::m_lpUnk[] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
CAutoApp::CAutoApp()
{
	EnableAutomation();
	for (int i=0; i < MAXNUMCONN && NULL != m_lpUnk[i]; i++);
	if (i < MAXNUMCONN)
		m_lpUnk[i] = GetInterface(&IID_IUnknown);
}

Whenever a client closes, CMainFrame::OnClose is called in the server. So I have the following code to implement 5 and 7 in OnClose():

//see if any clients are still connected
int i=0;
while(i < MAXNUMCONN && NULL != CAutoApp::m_lpUnk[i])
{
    try
    {
        CAutoApp::m_lpUnk[i]->AddRef();
        CAutoApp::m_lpUnk[i++]->Release();
    }
    catch(...)
    {
        //connection no longer exists, remove from array
        for(int j=i; j<MAXNUMCONN-1 && NULL != CAutoApp::m_lpUnk[j]; j++)
            CAutoApp::m_lpUnk[j] = CAutoApp::m_lpUnk[j+1];
    }
}

//if connected to at least one client
if (NULL != CAutoApp::m_lpUnk[0])
{
    if (IsWindowVisible())
    {
        if (IDNO == AfxMessageBox("One or more remote connections is still active. Exit anyway?", MB_YESNO))
            //user decides not to close application
            return;
    }
    else
        //a client disconnected but do not close because other client(s) remain
        return;
}
            .....
        CMDIFrameWnd::OnClose();

This works, although maybe it's a no-no to use a try-catch this way. If there's a better way to do it, I'd like to know.

To implement (6), I have the following:

void CMainFrame::OnCloseconnections() 
{
	if (IDNO == AfxMessageBox("This will close all connections. Are you sure?", MB_YESNO))
		return;

	//close all connections
	for (int i=0; NULL != CAutoApp::m_lpUnk[i]; i++)
	{
		try
		{
			while(CAutoApp::m_lpUnk[i]->Release());
		}
		catch(...)
		{
		}
		CAutoApp::m_lpUnk[i] = 0;
	}
}

This works, however when a user attempts to close my application, it crashes somewhere in the OLE dlls. There must be a better way to do what I'm trying to do?

Thanks,
Gary

How to read Swedish word correctly

njhy18-Mar-08 7:54

njhy

18-Mar-08 7:54

I have a program that reads contents of a text file. There is this one Swedish word that gives me trouble. The word is KALVFÄRS. When my program reads, read buffer contains KALVFÃ„RS, which is different than what's in the file. But the word is shown correctly in EditPlus. I need my program to read the way EditPlus reads.

I first used Win32 api to read, then tried with file io functions (fread) to read. I still have not found a way to read it correctly. Does any one know how EditPlus reads, or is there anything I should try?

BTW, language is set to Swedish in my computer.

Re: How to read Swedish word correctly

Maxwell Chen18-Mar-08 8:37