C / C++ / MFC

Re: how to use MFC data Types in win 32 dll

10-Dec-07 22:37

kmani_soft wrote:
i want to use CString how can i use this ...tell me how to use the MFC data types with in Win 32 Dll Application

Why?

use std::string instead.

Anyway, have a look at http://msdn2.microsoft.com/en-us/library/5bzxfsea(VS.80).aspx[^]
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Mark Salsbery11-Dec-07 6:23

Mark Salsbery

11-Dec-07 6:23

CStringT is no longer just part of MFC. Just use the appropriate
header file:

Header       Use for
 
cstringt.h   MFC-only string objects
atlstr.h     Non-MFC string objects

Mark Salsbery
Microsoft MVP - Visual C++

Java | [Coffee]

string array v.s. int array

George_George10-Dec-07 18:51

10-Dec-07 18:51

Hello everyone,

I find strange result in the following program.

1. For string array, dereferencing it will result in the string itself, but for int array, dereferencing it will result in the address of the array;

2. When dereferencing it twice (operator **), why the result is always the 1st element in both string array sample and int array sample?

int main()

{
	wchar_t me[] = L"Hello World \n";
	wchar_t (*me2_ptr)[14] = &me;
	wcout << *me2_ptr << endl;	// output Hello World
	wcout << **me2_ptr << endl; // output H

	int values[] = { 10, 20, 30, 40, 55, 60, 70, 80, 90, 100 };
	int (*pval)[10] = &values;
	wcout << *pval << endl;  // output 0x0017f6f0
	wcout << **pval << endl; // output 10

	return 0;
}

thanks in advance,
George

Doc Lobster10-Dec-07 22:10

Doc Lobster

10-Dec-07 22:10

Hi,

I'm not exactly sure why you are using wchar_t (*me2_ptr)[14] = &me; and its equivalent for the int.

However, look at things like this:

me2_ptr - is a pointer on a pointer on a wchar_t
*me2_ptr - is a pointer on a wchar_t
**me2_ptr - is a wchar_t

pval - is a pointer on a pointer on a int
*pval - is a pointer on a int
**pval is a int

If you call operator<< on a pointer on a wchar_t it assumes its target is a c-string and delivers the string itself. If you call operator<< on a pointer on a int it just delivers the value of the pointer. This is just the way operator<< is implemented.

George_George10-Dec-07 22:33

10-Dec-07 22:33

Thanks Doc,

Why *me2_ptr - is a pointer on a pointer on a wchar_t*? I think &me is a pointer to wchar_t, right?

Since in the following code, you can see &me is the same as me,

int main()
{
	char buf[] = "Hello World \n";

	_ASSERT (buf == &buf);

	return 0;
}

regards,
George

CPallini10-Dec-07 22:21

10-Dec-07 22:21

The depicted behavior is not so strange...

George_George wrote:
1. For string array, dereferencing it will result in the string itself, but for int array, dereferencing it will result in the address of the array;

In fact the behavior is quite similar: the name (or the address-of operator & applied on the name, remembering past posts... Smile | :)

) of the int array returns the address of the memory containing the integer values as well the name of the character array returns the address of the memory containing the character values;
you find a noticeable difference in the output only because a (C-like) string is nothing more than the pointer to the memory holding the zero-terminated character sequence, hence whenever wcout finds a (wide) character pointer, it prints the characters belonging to the pointed memory.

George_George wrote:
When dereferencing it twice (operator **), why the result is always the 1st element in both string array sample and int array sample?

Again, nothing strange here. Given a int pointer, say int *p, deferencing it means: "take the content of the pointed memory", namely the integer value at address p (that coincide with the first int element of the array). The same point applies to the character array.

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

George_George10-Dec-07 22:40

Re: string array v.s. int array [modified]

10-Dec-07 22:40

Hi CPallini,

What makes me confused is, in my test program before, the address of a string array should be the same as the string array itself. For example below, buf is the same as &buf.

int main()
{
	char buf[] = "Hello World \n";

	_ASSERT (buf == &buf);

	return 0;
}

I think in the code posted in the question, me2_ptr = &me, and it is the same as me, without dereferencing it, if we simply wcout << me2_ptr, result should be the same as wcount << me? Why we need to dereferencing it by operator * in order to get the same output of wcout << me?

regards,
George

CPallini10-Dec-07 22:51

10-Dec-07 22:51

Because you defined (correctly) it as pointer to an array address (i.e. another pointer), i.e.
*me2_ptr contains the address of me (the same address returned by &me).
Hence me2_ptr isn't a pointer to w_chars, but instead a pointer to a pointer of w_charss (added: that turns out to be the same address...).

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

modified on Tuesday, December 11, 2007 5:41:54 AM

George_George10-Dec-07 23:15

10-Dec-07 23:15

Hi CPallini,

If you have Visual Studio at hand, you can debug my sample program, and you can find that me is the same as me2_ptr (you can watch it), so me2_ptr is the same as me, I do not know why *me2_ptr is also the same as me?

regards,
George

CPallini10-Dec-07 23:41

10-Dec-07 23:41

You're right. *me2_ptr and me2_ptr both hold the same address (but are different types, this way wcout behaves differently on them), this probably is related to the fact that dereferencing an array name (i.e. *me2_ptr) should return the same address returned by the array name itself.

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

George_George11-Dec-07 1:54

11-Dec-07 1:54

Thanks CPallini,

I think you mean,

1. *me2_ptr is value of array type, and wcout is overloaded to print out the string array;
2. me2_ptr is address of array type, and wcount will print the address of array.

Right?

regards,
George

CPallini11-Dec-07 2:11

11-Dec-07 2:11

Technically the ostream extraction operator << is overloaded, but, poorly speaking the answer is yes.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Iain Clarke, Warrior Programmer

Iain Clarke, Warrior Programmer11-Dec-07 6:08

11-Dec-07 6:08

Cpallini has already explained at some length (to me too!) how the address of an array has the same value for convenience to printf (and it's relations).

The two bits of code you've shown do the same thing with derefencing. The only difference is that the wcout is clever enough to go "oh, I won't give a number, I'll give a lump of text - aren't I helpful?".

The short answer to question 2
BECAUSE.

Longer answer...
Because it has been defined that way by people cleverer than us.

Is this feature causing you problems?

Iain.

George_George11-Dec-07 21:14

Cursor color in resource editor

11-Dec-07 21:14

Thanks Iain,

My question is answered.

regards,
George

WM_CTLCOLOR

Tara1410-Dec-07 17:42

Tara14

10-Dec-07 17:42

Hi,

I am using WM_CTLCOLOR to make the static text transparent and change the font and colour. Please can you tell me how to do the font-clean-up action if any is required here?

HBRUSH CF4_NewEstimate::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor) 
{
	HBRUSH hbr = CResizableFormView::OnCtlColor(pDC, pWnd, nCtlColor);


	CFont *m_pFont = new CFont;
	m_pFont->CreateFont(12,0,0,0,600,0,0,0,0,0,0,ANTIALIASED_QUALITY,0,"MS Sans Serif");
	CFont *pOldFont = NULL;
	
// Make transparent static control
	switch (nCtlColor)
	{
		case CTLCOLOR_STATIC:
			pDC->SelectObject(m_pFont);
			hbr = (HBRUSH)::GetStockObject (HOLLOW_BRUSH);
			pDC->SetBkMode (TRANSPARENT);
			pDC->SetTextColor(RGB(255,128,0));
			
		
		break;
	}
	
	
	return hbr;


}

Thanks.

Fortitudine Vincimus!

Re: WM_CTLCOLOR

Naveen10-Dec-07 18:22

Naveen

10-Dec-07 18:22

Tara14 ase CTLCOLOR_STATIC: pDC->SelectObject(m_pFont);

This is not the correct way to change the font of a window. You should call the SetFont() function to change the font and this need to be done only once( in OnInitdialog() or OnIntitialUpdate() function etc ).

nave

[OpenedFileFinder]

followait10-Dec-07 16:23

10-Dec-07 16:23

I want to add a 16-bit color cursor.
But when I insert a new cursor, there is a default monochrome one, and LoadCursor will use that one by default. How to use 16-bit cursor?

Nelek10-Dec-07 23:23

Nelek

10-Dec-07 23:23

Just design your cursor in the resource editor, give it a IDC_NAME and use ::LoadCursor and ::SetCursor.

if you load it but not set it active...

Greetings.
--------
M.D.V. Wink | ;)

followait11-Dec-07 3:47

11-Dec-07 3:47

setted, but the monochrome one using the same ID takes effect

Nelek11-Dec-07 22:32

Nelek

11-Dec-07 22:32

This is to set the normal white arrow that is always in all MFC-Win32 app by default.

	HCURSOR m_hCursor;   //<--- this is in the header
;
	//Now in the cpp
	m_hCursor=AfxGetApp()->LoadStandardCursor(IDC_ARROW);	// Loading normal cursor
	if (m_hCursor)							// If load works good
		::SetCursor (m_hCursor);				// Change to selected cursor

And here I set my own drawn cursor

m_hCursor=AfxGetApp()->LoadCursor(IDC_SELPOINT); // Loading owner cursor
if (m_hCursor)                      // If load ok
    ::SetCursor (m_hCursor);            // Change to selection cursor

Note that the ID that I use to load my own cursor is the ID that I give to the cursor in my resources editor.

What are you making?

Greetings.
--------
M.D.V. Wink | ;)

followait11-Dec-07 23:02

Is floating point number mathematical integer?

11-Dec-07 23:02

That's just what I do.
The problem is that I added a "16-bit color" cursor, not the default monochrome one. But LoadCursor will load the monochrome one instead of the "16-bit color" one. They have the same ID.

Oliver12310-Dec-07 14:15

Oliver123

10-Dec-07 14:15

How can one determmine if a given floating point variable is a mathematical integer (1,2,3,4,5...)? I figured I could divide by one and check for zero as a remainder. Doesn't work.

float fNumber = 861;
float one = 1;

fmod(fNumber, one)
modf(fNumber, one)

Both of these return a value of .9998936354755 (or some other decimal very close to 1).

I've tried various combinations of float and double, but get the same results.

Ideas? Thanks.

Re: Is floating point number mathematical integer?

followait10-Dec-07 16:38