C / C++ / MFC

16-Apr-06 22:46

Hi friends,
1)What is user of global static variables.
2) can i user those vars in other files with extern keyword?

Vikram S

sunit516-Apr-06 23:02

sunit5

16-Apr-06 23:02

vikrams wrote:
2) can i user those vars in other files with extern keyword?

it has an internal linkage ie its scope is in the translation unit where it is defined.

vikrams wrote:
2) can i user those vars in other files with extern keyword?

u have to remove the static keyword

never say die

-- modified at 5:04 Monday 17th April, 2006

vikramlinux16-Apr-06 23:13

16-Apr-06 23:13

Can u please put some more light on "translation unit" concept in terms of source & header files?

vikramlinux17-Apr-06 0:37

17-Apr-06 0:37

Hi Friends,
After some analysis I got following answers
1) When u compile your files(any type of project). each cpp/cxx/C file treated as separate translation unit
2) Object file will be created for each one of them

So for static variables

1) If the static variable in declared in some other cpp/cxx/c file, U can not access it ( using extern keyword) as it becomes as private for that file/translation unit.
2) If u declared global static variable in header file then each translation unit will get copy of it and also your final exe will contain mutiple instances of that global variable
for each file contents (means the functions/classes... inside file ).

Experts.. Please correct me if there is any incorrectness.

VikramS

vikramlinux17-Apr-06 0:38

Convert STL string --> TCHAR (clairification)

17-Apr-06 0:38

Timing diagram

RockyJames16-Apr-06 22:40

RockyJames

16-Apr-06 22:40

Hi,
Does any have idea of "Timing Diagram"..i want to implement it,pls help me out.

thanks in before
James rocky

Re: Timing diagram

David Crow17-Apr-06 3:38

David Crow

17-Apr-06 3:38

RockyJames wrote:
Does any have idea of "Timing Diagram"..

This could be most anything. Please elaborate.

"Let us be thankful for the fools. But for them the rest of us could not succeed." - Mark Twain

"There is no death, only a change of worlds." - Native American Proverb

chasetoys16-Apr-06 21:09

chasetoys

16-Apr-06 21:09

Hey sorry to repost, but no one seems to pay attention to posts that have some answers.

I am strying to take a STL string that I have and use it WIN32 API calls that require a LPTCSTR ( I think this is a const tstring). Anyways, I have tried the following header code, and it compiles, but I have no idea how to use the " typedef std::basic_string< TCHAR > tstring; " code... basically I want to do the following:

string stlStr;
LPTSTR sillyMicrosoftString = stringToLPTSTR(blah);

How can I make this work?

//header code in my file

#include <windows.h>
#include <stdio.h>
#define NULL 0
#include "LogFiles.h"
#include "TestPrint.h"
#include <string>
#include "TestPrint.h"
#include <iostream>
#include <conio.h>

typedef std::basic_string< TCHAR > tstring;

-- modified at 3:10 Monday 17th April, 2006

Hallery.Lai16-Apr-06 22:08

Hallery.Lai

16-Apr-06 22:08

you can convert string to "char *" first,then convert "char *" to LPTSTR.

chasetoys16-Apr-06 22:18

chasetoys

16-Apr-06 22:18

Could you show me an example please?

Thanks!

Hallery.Lai16-Apr-06 22:49

Hallery.Lai

16-Apr-06 22:49

string strA = "test string";
char *pTemp = (char *)strA.c_str();
TCHAR * s1=(TCHAR *)s;

chasetoys16-Apr-06 23:38

chasetoys

16-Apr-06 23:38

That doesn't work at all!

So I have the need to turn STL strings into LPTSTRs, and then take LPTSTRs back into strings...

Please help me solve this problem.

Thanks!

About draw a picture in dialog box

Michael Dunn17-Apr-06 8:09

Michael Dunn

17-Apr-06 8:09

See my C++ string guide: Part 1[^] Part 2[^]
Part 2 covers the various wrapper classes, but make sure you understand part 1 since that explains how encoding works.

--Mike--
Visual C++ MVP Cool | :cool:

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lisoft16-Apr-06 21:00

lisoft

16-Apr-06 21:00

I have a class that can draw picture in dialog box using the following code:

<br />
void CDialogbox::OnPaint()<br />
{<br />
	CPaintDC dc(this); // device context for painting<br />
	CRect m_rect;<br />
	GetWindowRect(m_rect);<br />
	//...<br />
	m_myclass.Draw(dc,m_rect); // Draw the image to dialog box<br />
		<br />
}<br />

These codes works fine as I just anticipated. But when I want to use memory DC for caching, it did not work:

<br />
void CDialogbox::OnPaint()<br />
{<br />
	CPaintDC dc(this); // device context for painting<br />
	CDC m_memdc;<br />
	m_memdc.CreateCompatibleDC(&dc); //Create a memory DC<br />
	CRect m_rect;<br />
	GetWindowRect(m_rect);<br />
	//...<br />
	m_myclass.Draw(dc,m_memdc); // First draw to memory DC<br />
	dc.BitBlt(m_rect.left,m_rect.right,m_rect.Width(),m_rect.Height(),&m_memdc,0,0,SRCCOPY); // Second copy from memory DC to Paint DC<br />
}<br />

Does anyone can help me? Confused | :confused:

Lisoft

Re: About draw a picture in dialog box

Le Thanh Cong16-Apr-06 22:59

Le Thanh Cong

16-Apr-06 22:59

m_myclass.Draw(dc,m_memdc); // First draw to memory DC???????????
Why parameter 2 is a DC

-----------------
conglt

Re: About draw a picture in dialog box

Nishad S16-Apr-06 23:27

Nishad S

16-Apr-06 23:27

The problem is you did not selected any bitmap to the memdc.
CreateCompatibleDC will create a dc with 1x1 pixel wide bitmap. So you have to create a bitmap also. See the example.

CPaint dc( this );
CDC dcMem;
dcMem.CreateCompatibleDC( &dc );
CBitmap bitmap;
bitmap.CreateCompatibleBitmap( &dc, width, height );
CBitmap* pOldBitmap = dcMem.SelectObject( &bitmap );
//
// Draw
//
dc.BitBlt( 0, 0, width, height, &dcMem, 0, 0, SRCCOPY );
dcMem.SelectObject( pOldBitmap );

GoodLuck!

- NS -

Re: About draw a picture in dialog box

lisoft17-Apr-06 17:34

lisoft

17-Apr-06 17:34

Thanks a lot, it works! Smile | :)

Lisoft

TAPI , COM

asdf175316-Apr-06 20:57

asdf1753

16-Apr-06 20:57

Dear Friends,
I try to work with TAPI3.0 that is COM based, so in create an COM object it returns "CoCreateInstance on TAPI failed"

<br />
	ITTAPI *TObj;<br />
	HRESULT hr;<br />
    hr = CoCreateInstance(<br />
                          CLSID_TAPI,<br />
                          NULL,<br />
                          CLSCTX_INPROC_SERVER,<br />
                          IID_ITTAPI,<br />
                          (LPVOID *)&TObj<br />
                         );<br />
    if ( FAILED(hr) )<br />
    {<br />
		MessageBox("CoCreateInstance on TAPI failed");<br />
    }<br />

is there any one help me ?

YaronNir16-Apr-06 21:39

YaronNir

16-Apr-06 21:39

What is the hr result when CoCreateInstance Fails?
look the result in the error lookup.

hope this helps

Yaron

Ask not what your application can do for you,
Ask what you can do for your application

asdf175316-Apr-06 23:07

asdf1753

16-Apr-06 23:07

it says in HRESULT "CoInitialize has not been called."

YaronNir17-Apr-06 0:31

YaronNir

17-Apr-06 0:31

There ya go Smile | :)

in order to call CoCreateInstance, you need to load the COM libraries. this is done by
CoInitialize method (check out MSDN for more information)

don't forget to call CoUninitialize when done using the COM libraries

good luck

Yaron Sigh | :sigh:

Ask not what your application can do for you,
Ask what you can do for your application