C / C++ / MFC

Re: ReleaseBuffer() of CSimpleString is not working.

3-Feb-11 19:10

MSDN[^] says that the lpszPath parameter should have MAX_PATH of space allocated.

This should also correct the crash.

PathCompactPath(pDC->GetSafeHdc(),strMPGFilePath.GetBuffer(MAX_PATH),oRc.Width());
strMPGFilePath.ReleaseBuffer();

Amrit Agr3-Feb-11 21:38

Amrit Agr

3-Feb-11 21:38

My problem has solved.
Thank you very much.

Dos command

MsmVc3-Feb-11 18:17

MsmVc

3-Feb-11 18:17

Hi All

I try to run dos command through mfc vc++.I know run dos command through .bat file.But my question is

Can i run dos command directly from code?

Please help me

Rajesh R Subramanian3-Feb-11 18:39

Rajesh R Subramanian

3-Feb-11 18:39

Which DOS command are you looking to run from your c++ code?

"Real men drive manual transmission" - Rajesh.

Andrew Brock3-Feb-11 18:49

3-Feb-11 18:49

The system()[^] command can be used to execute an operating system function.
Also read about it here[^].

You could also use CreateProcess[^] if you are wanting to execute a program

MsmVc4-Feb-11 0:27

MsmVc

4-Feb-11 0:27

Thanks problem solved

Re: Dos comman

Cool_Dev3-Feb-11 23:03

Cool_Dev

3-Feb-11 23:03

MsmVc wrote:
I try to run dos command through mfc vc++.

If you just want to run a command from you application, go fot the functions mentioned in earlier reply.
If you are aiming to run a command and show its output in a window in your application, you have to go for Pipe communication.

csrss3-Feb-11 23:25

csrss

3-Feb-11 23:25

C WinAPI solution (you can adopt it in mfc easily i think):

#include <windows.h>
#include <stdio.h>

char * ExecuteCMD(char * command)
{
		SECURITY_ATTRIBUTES sec;
		PROCESS_INFORMATION pi;
        STARTUPINFO si;
		HANDLE hOutR, hOutW;
		DWORD BTAvail;
		char * Result = NULL;
		char * cmdline = NULL;
		char cmdpath[256];
		OSVERSIONINFO OSVersionInfo;
		DWORD Read = 0;

			ZeroMemory(&pi, sizeof(PROCESS_INFORMATION));
			ZeroMemory(&sec, sizeof(SECURITY_ATTRIBUTES));
			sec.nLength = sizeof(SECURITY_ATTRIBUTES);
			sec.bInheritHandle = TRUE;
			sec.lpSecurityDescriptor = NULL;
	
	if (CreatePipe(&hOutR, &hOutW, &sec, 0)) 
	{
				ZeroMemory(&si, sizeof(STARTUPINFO));
				si.cb = sizeof(STARTUPINFO);
				si.hStdOutput = hOutW;
				si.dwFlags = STARTF_USESTDHANDLES|STARTF_USESHOWWINDOW;

			cmdline = (char *) GlobalAlloc(GMEM_FIXED, (7 + lstrlen(command)));
			lstrcat(lstrcpy(cmdline, " /a /c "), command);

			OSVersionInfo.dwOSVersionInfoSize = sizeof (OSVERSIONINFO);
			GetVersionEx (&OSVersionInfo);

			if (OSVersionInfo.dwPlatformId == VER_PLATFORM_WIN32_NT)
			{
				GetEnvironmentVariable("ComSpec", cmdpath, 2048);
			}

		if (CreateProcess(cmdpath, cmdline, &sec, &sec, TRUE, NORMAL_PRIORITY_CLASS, NULL, NULL, &si, &pi))
		{
			WaitForSingleObject(pi.hProcess, INFINITE);
			CloseHandle(pi.hThread);
			CloseHandle(pi.hProcess);
			PeekNamedPipe (hOutR, NULL, 0, NULL, &BTAvail, NULL);
				if (BTAvail > 0)
				{
					Result = (char *) GlobalAlloc(GMEM_FIXED, BTAvail + 1);
					ReadFile(hOutR, Result, BTAvail, &Read, NULL);
					Result[BTAvail] = '\0';
					OemToChar(Result, Result);
					return Result;
				}
		}
}
	return NULL;
}

int main(int argc, char **argv)
{
	char *cmd = ExecuteCMD("dir");
	puts(cmd);
}

011011010110000101100011011010000110100101101110
0110010101110011

Would you all call this namespace abuse?

MsmVc4-Feb-11 1:11

MsmVc

4-Feb-11 1:11

Thanks for solution

Problem solved

asincero3-Feb-11 14:06

asincero

3-Feb-11 14:06

I've been thinking of adopting a new style of namespace use. Well, new to me because I've never seen it used this way anywhere else. The common thing to do in C++ is to have one class to be declared per header file. The only other things that would be declared in the header would be closely related functions and types (helper functions, friend classes, typedefs, enums, etc.). Often, the header file is named after the class.

I propose declaring each class inside it's own namespace. The namespace would be named after the class, except in all lowercase with words seperated by underscores. Classes would be named using the traditional PascalCasingScheme. Related classes and functions would go inside this namespace. Any public nested classes, typedefs, and enums would be at namespace scope instead of being declared inside the class.

For example, this is the before:

// in fancy_widget.h

class FancyWidget
{
public:
    typedef std::vector<std::string>    WidgetIds;
    typedef std::map<std::string, int>  WidgetPrices;

    enum WidgetColors
    {
        RED,
        WHITE,
        BLUE
    };

    class Exception : public std::exception
    {
        ...
    };

    class InvalidWidgetException : public Exception
    {
        ...
    };

    ...
};

and this is the after:

// in fancy_widget.h

namespace fancy_widget
{
    typedef std::vector<std::string>   WidgetIds;
    typedef std::map<std::string, int> WidgetPrices;    

    enum WidgetColors
    {
        RED,
        WHITE,
        BLUE
    };

    class Exception : public std::exception
    {
        ...
    };

    class InvalidWidgetException : public Exception
    {
        ...
    };

    class FancyWidget
    {
        ...
    };
}

I tend to make things that are closely related to a class nested inside the class declaration, friend classes in particular. However, this practice always led to a convoluted class declaration. Using this style moves it out of the class declaration, but still conveys a strong association with that class through the namespace.

I can't think of any negatives to this approach, hence why I'm posting this to the forum. I don't think the extra typing whenever you needed to use anything inside "fancy_widget" would be a bother and if it did there's always the "using" keyword. Anybody see anything wrong with doing this?

This sort of thing seems to be somewhat common in Python (except they frown upon using underscores in package names). Which is why I've started thinking about carrying it over into my C++.

Madhu Nair3-Feb-11 16:33

Madhu Nair

3-Feb-11 16:33

I don't think its an abuse, thats how namespaces have to be used.

typedef std::vector<std::string>   WidgetIds;    
typedef std::map<std::string, int> WidgetPrices;

Will be global variables in second approach, are you OK with that ?

asincero3-Feb-11 16:45

asincero

3-Feb-11 16:45

Madhu Nair wrote:
typedef std::vector<std::string> WidgetIds;
typedef std::map<std::string, int=""> WidgetPrices;

Will be global variables in second approach, are you OK with that ?

What do you mean? Those are typedef's for std::vector and std::map and would be used like so:

fancy_widget::WidgetIds foo;
fancy_widget::WidgetPrices bar;

Stefan_Lang3-Feb-11 21:55

Stefan_Lang

3-Feb-11 21:55

Yes and no.

Yes, they are globally accessible, but that was also true in the first approach, since they've been declared public.

No they are not global, because, technically, only things declared outside a struct, class or namespace are considered global. These symbols are local to the newly defined namespace. It's about as close to global that you can get though, since - similar to true global definitions - the declaration s of the elements of a namespaces may be spread out over the codebase, so you're not guaranteed to see everything that's in a namespace when you look at a namespace declaration.

This can be considered a disadvantage, but it is also an advantage, as you can later extend a namespace for internal use without having to change a header and thus the interface of whatever you're trying to encapsulate. You might also deliberatly spread different parts of the namespace over several headers in order to minimize dependencies and thus reduce compile times.

Alain Rist3-Feb-11 20:31

Alain Rist

3-Feb-11 20:31

Hi,

asincero wrote:
I can't think of any negatives to this approach

The only drawback is that a class can be used as template argument and a namespace cannot. If not relevant in your case, the namespace approach is indeeed cleaner.

cheers,
AR

When the wise (person) points at the moon the fool looks at the finger (Chinese proverb)

Error in Release() throw function

bob169724-Feb-11 5:03

bob16972

4-Feb-11 5:03

A related question I have regarding the use of namespaces in C++ (assuming Visual Studio) is in the past, I've found using the "ClassWizards" (or whatever they call the current feature) put any new methods outside of the namespace curly brackets requiring me to move new methods into the namepace.

Did they finally fix that and if so what version of Visual Studio are you using that places new methods correctly in their namespace?
thanks.

Change Image size

john56322-Feb-11 20:32

john5632

2-Feb-11 20:32

Hi,

How can I change the image attribute using gdi+?
I need to change the image size using gdi+.

Re: Change Image size

Madhu Nair2-Feb-11 21:17

Madhu Nair

2-Feb-11 21:17

john5632 wrote:
I need to change the image size using gdi+.

A solution in .NET, enough for understanding the method applied.

Resizing a Photographic image with GDI+ for .NET[^]

Re: Change Image size

S p k 5213-Feb-11 1:00

S p k 521

3-Feb-11 1:00

Hi John,

You can use DrawImage() to rescale images...

Regards,
Spk521

Re: Change Image size

Cool_Dev3-Feb-11 2:01

Cool_Dev

3-Feb-11 2:01

Image::GetThumbnailImage and Bitmap::SetResolution (see eg. in earlier reply) method are apt for this.
DrawImage() method simply draws the image with given dimension, it doesn't provide option to alter the source image, or to retrieve resized image.

Anu_Bala2-Feb-11 19:30

Anu_Bala

2-Feb-11 19:30

Im using VS2008.
Im sending data to LED in external device thorugh serial port by given in set of format for glowing LED.
But it show error on Release() in nRef!=0 line.
Actually it works fine in VC6.0Now im converting that to VS2008.

struct SLEDFrame
{
	char *idtfr,*Data1,*Data2;
};

SLEDFrame btnLED[] = {
						
"0x53", "0x30", "0x30", 		//0			
"0x53", "0x30", "0x31",  		//1	
"0x53", "0x30", "0x32",  		//2	
"0x53", "0x30", "0x33",  		//3	
"0x53", "0x30", "0x34",  		//4
};

void CMSCOMMDlg::setLED(int pLEDNo, BOOL pState)
{

	BYTE bID, bByte1, bByte2, bState, bCheckSumByte1, bCheckSumByte2;

	if (pState)
		bState = 0x31;   //ON
	else 
		bState = 0x30;   //OFF
	

CString tempStr, C1, C2;

tempStr = btnLED[pLEDNo-1].idtfr;
tempStr = tempStr.Mid(2);    
sscanf(tempStr, "%x", &bID);

tempStr = btnLED[pLEDNo-1].Data1;
tempStr = tempStr.Mid(2);    
sscanf(tempStr, "%x", &bByte1);

tempStr = btnLED[pLEDNo-1].Data2;
tempStr = tempStr.Mid(2);    
sscanf(tempStr, "%x", &bByte2);

BYTE bSum = bByte1 + bByte2 + bState; 	
tempStr.Format("%x",bSum);

C1 = "0x3" + tempStr.Left(1);
C2 = "0x3" + tempStr.Right(1);
sscanf(C1, "%x", &bCheckSumByte1);
sscanf(C2, "%x", &bCheckSumByte2);


	//To send data use this code:
	CByteArray btArray;
 
	btArray.Add (bID); 	  		//Identifier byte
	btArray.Add (bByte1); 		// DataByte 1
	btArray.Add (bByte2); 		// DataByte 2
	btArray.Add (bState); 		//Status Byte
	btArray.Add (bCheckSumByte1); 	//CheckSumByte1
	btArray.Add (bCheckSumByte2); 	//CheckSumByte2
	
	COleVariant var(btArray);
	m_Comm.SetOutput(var);	// Send the data. 

	
} //It shows the error when the cursor comes out of this function.

The error occurs in

void Release() throw()
{
ATLASSERT( nRefs != 0 );
if( _AtlInterlockedDecrement( &nRefs ) <= 0 )
{
pStringMgr->Free( this );
}
}

Anu

Re: Error in Release() throw function

Andrew Brock2-Feb-11 19:43

Re: Error in Release() throw function

2-Feb-11 19:43

Why are you using strings? This is slow and pointless.
You should read up on bitwise operations[^] such as shift and AND

struct SLEDFrame {
	BYTE idtfr;
	BYTE Data1;
	BYTE Data2;
};

SLEDFrame btnLED[] = {
	{ 0x53, 0x30, 0x30 }, 					
	{ 0x53, 0x30, 0x31 },  			
	{ 0x53, 0x30, 0x32 },  			
	{ 0x53, 0x30, 0x33 },  			
	{ 0x53, 0x30, 0x34 },  		
	{ 0x53, 0x30, 0x35 }, 
}

void CMSCOMMDlg::setLED(int pLEDNo, BOOL pState) {
	BYTE bState;
	if (pState) {
		bState = 0x31;   //ON
	} else  {
		bState = 0x30;   //OFF
	}
	BYTE bID = btnLED[pLEDNo-1].idtfr;
	BYTE bByte1 = btnLED[pLEDNo-1].Data1;
	BYTE bByte2 = btnLED[pLEDNo-1].Data2;
	BYTE bSum = bByte1 + bByte2 + bState; 	
	BYTE bCheckSumByte1 = 0x30 | (bSum >> 4);
	BYTE bCheckSumByte2 = 0x30 | (bSum & 0x0F);
	
	//To send data use this code:
	CByteArray btArray;
	btArray.Add(bID); 	  //Identifier byte
	btArray.Add(bByte1); // DataByte 1
	btArray.Add(bByte2); // DataByte 2
	btArray.Add(bState); //Status Byte
	btArray.Add(bCheckSumByte1); //CheckSumByte1
	btArray.Add(bCheckSumByte2); //CheckSumByte2
	
	COleVariant var(btArray);
	m_Comm.SetOutput(var);	// Send the data.
}

Anu_Bala2-Feb-11 20:05

Anu_Bala

2-Feb-11 20:05

Can you tell me how can i convert CString to BYTE.
I used
CString C2 = "0x30h"
BYTE bCheckSumByte2 ;
bCheckSumByte2 = (BYTE)(LPCSTR)C2;

But it doesnt work.

Anu

Re: Error in Release() throw function

Andrew Brock2-Feb-11 20:35