C / C++ / MFC

Re: How can I have several hundred of #if defined(XXX) ... #endif in an easy-to-read table format?

10-Oct-19 4:27

Yes, if worse comes to worse I will do this. Is there source code available somewhere for a "preprocessor light" that can automatically detect #defines that are evaluated to numbers?

CPallini10-Oct-19 6:12

CPallini

10-Oct-19 6:12

Very probably there is, but, unfortunately, I am not aware of. I do use a little Lua script for the purpose. Lua features powerful string manipulation functions and it is a very enjoyable scripting language. You might also use a more popular scripting language, like, for instance, Python (another option is, if you like it, using the C++ 11 regex classes).

Problem with AlphaBlend.

Member 126614649-Oct-19 6:57

Member 12661464

9-Oct-19 6:57

I display the 32 bit icon with transparency using the AlphaBlend function. If the window with the icon is moved partially outside the monitor screen, the transparent area in some places is filled. Damaged places with partial transparency.. Any idea what it might be?

modified 9-Oct-19 13:23pm.

Re: Problem with AlphaBlend.

Richard MacCutchan9-Oct-19 8:49

Re: Problem with AlphaBlend.

9-Oct-19 8:49

Member 12661464 wrote:
Any idea what it might be?

Maybe the Window is not getting refreshed properly. Do you have code that is controlling when the icon gets painted?

Member 126614649-Oct-19 9:09

Member 12661464

9-Oct-19 9:09

I just put the following code in the OnPaint () handler.

C++

CPaintDC dc(this);
	CDC *psrcDC = m_PictureControl.GetDC();
	CDC dstDC;
	dstDC.CreateCompatibleDC(psrcDC);
HBITMAP oldBmp = (HBITMAP)SelectObject(dstDC.m_hDC, startBitmap);
BLENDFUNCTION blend = { AC_SRC_OVER, 0,255, AC_SRC_ALPHA };
AlphaBlend(psrcDC->m_hDC, 0, 0, iWidth, iHeight, dstDC.m_hDC,0, 0, iWidth, iHeight, blend);
	DeleteObject(oldBmp);
	DeleteObject(startBitmap);
	ReleaseDC(psrcDC);

Re: Problem with AlphaBlend.

Richard MacCutchan9-Oct-19 9:34

Passing a "value", that was either #defined or #undef, into a macro and check if it was defined?

9-Oct-19 9:34

Sorry, I cannot see anything obvious. Also, I am afraid I don't use MFC, so cannot try a similar test.

arnold_w9-Oct-19 6:07

Re: Passing a "value", that was either #defined or #undef, into a macro and check if it was defined?

9-Oct-19 6:07

I want to create a macro that is fully executed at compile time (not runtime). If two values are both defined, then I want to check if they are equal. If at least one of them is not defined, then nothing should happen. I have come halfway, the following works great:

C++

#define VALIDATE_ADDR(ADDR1,ADDR2)  _Static_assert(ADDR1 == ADDR2, #ADDR1 " is not equal to " #ADDR2);

However, when I try to nest that macro into another macro, then I run into trouble:

C++

#define VALIDATE_ADDR_IF_THEY_BOTH_EXIST(ADDR1,ADDR2)   \
#if defined(ADDR1) && defined(ADDR2)                    \
   VALIDATE_ADDR(ADDR1, ADDR2)                          \
#endif

Can someone please help me so I can do checks like this:

C++

#define MY_ADDR_1  (1)
#define MY_ADDR_2  (2)
#define MY_ADDR_3  (3)
#ifdef MY_ADDR_4
#undef MY_ADDR_4
#endif

VALIDATE_ADDR_IF_THEY_BOTH_EXIST(MY_ADDR_1, MY_ADDR_2); // Compile time error since MY_ADDR_1 != MY_ADDR_2
VALIDATE_ADDR_IF_THEY_BOTH_EXIST(MY_ADDR_3, MY_ADDR_4); // Compiles just fine since MY_ADDR_4 is not defined

k50549-Oct-19 6:48

k5054

9-Oct-19 6:48

AFAIK, that's not possible, since the # token is reserved for stringifying macro parameters within the macro expansion.

Also, I see that your definition for VALIDATE_ADDR ends in a semicolon. In general, you do not want to end a macro with a semicolon, since this can lead to, in the best case, a compiler error, and in the worst case, a subtle and hard to find bug.

Re: Passing a "value", that was either #defined or #undef, into a macro and check if it was defined?

Richard MacCutchan9-Oct-19 8:47

Re: Passing a "value", that was either #defined or #undef, into a macro and check if it was defined?

9-Oct-19 8:47

Macros are purely compile time. If you want runtime checks then use functions. Macros such as the above tend to be more trouble than they are worth.

arnold_w9-Oct-19 9:14

Re: Passing a "value", that was either #defined or #undef, into a macro and check if it was defined?

9-Oct-19 9:14

What do you mean? I've clearly stated I want compile time execution, not runtime execution of this macro. Are you thinking of the _Static_assert function? It is executed at compile time, I think it's a feature built into the gcc compiler.

Richard MacCutchan9-Oct-19 9:51

Re: Passing a "value", that was either #defined or #undef, into a macro and check if it was defined?

9-Oct-19 9:51

Sorry I misread the question. I have tried a number of variants but cannot get it to work. it would appear that #define statements are not accepted inside a macro definition.

arnold_w9-Oct-19 9:18

9-Oct-19 9:18

Btw, I don't need the VALIDATE_ADDR macro for anything, it's perfectly fine to replace it with the _Static_assert directly, if that makes anything easier.

String Table MFC vc++

Member 145755569-Oct-19 1:59

Re: String Table MFC vc++

9-Oct-19 1:59

I have some hard coded strings which I wanted to add to the String Table and load that string from the string table.

From the resource view, i go to the string table and gave ID,value and caption there.

and tries to load by doing this.

C++

CString temp;
temp.LoadString(IDS_STRING1);

But its giving me IDS_STRING1 is undefined. What is the correct way to do this?

Thanks in advance.

Member 145755569-Oct-19 2:04

Re: String Table MFC vc++

9-Oct-19 2:04

I found what I did wrong. Thanks Smile | :)

Maximilien9-Oct-19 22:00

Maximilien

9-Oct-19 22:00

what was wrong ? how did you fix it ?

I'd rather be phishing!

Re: String Table MFC vc++

Member 145755569-Oct-19 22:20

Singleton Design Pattern for Database connection in MFC vc++

9-Oct-19 22:20

I gave the value which is already there.. I gave a different number which is not already used and that solve my problem.

Member 145755566-Oct-19 18:24

Re: Singleton Design Pattern for Database connection in MFC vc++

6-Oct-19 18:24

How to implement singleton design pattern for database connection in MFC vc++?.

_Flaviu6-Oct-19 19:38

Re: Singleton Design Pattern for Database connection in MFC vc++

6-Oct-19 19:38

Use this singleton pattern into extention of CDatabase class. A little sample of how to extend this class can be found here: CDatabaseExt - A Simple Way to Connect to a Database and Retrieve Data[^]. You can easily change CDatabaseExt constructor as private and made access method GetInstance() as public.

Member 145755566-Oct-19 21:29

Re: Singleton Design Pattern for Database connection in MFC vc++

6-Oct-19 21:29

I have created like this. Am I going in the right direction?
Thanks in advance.

C++

#include <afxdb.h>

#pragma once

// DatabaseSingleton command target

class DatabaseSingleton : public CDatabase
{
	static DatabaseSingleton* _instance;
	DatabaseSingleton();
public:
	//DatabaseSingleton();
	static DatabaseSingleton* GetInstance();
	virtual ~DatabaseSingleton();
private:
	CString DSN;
	CString UID;
	CString PWD;
	CString ConnectionString;
};

C++

// DatabaseSingleton.cpp : implementation file
//

#include "stdafx.h"
#include "Medication_Administration.h"
#include "DatabaseSingleton.h"


// DatabaseSingleton

DatabaseSingleton::DatabaseSingleton():DSN(_T("DemoDB")),UID(_T("root")),PWD(_T("root"))
{
	ConnectionString.Format(_T("DSN=%s;UID=%s;PWD=%s"), DSN, UID, PWD);
	OpenEx(ConnectionString);
}

DatabaseSingleton::~DatabaseSingleton()
{
	Close();
}


// DatabaseSingleton member functions
DatabaseSingleton* DatabaseSingleton::GetInstance()
{
	if (_instance == NULL)
	{
		_instance = new DatabaseSingleton();
	}
	return _instance;
}

_Flaviu6-Oct-19 21:55

6-Oct-19 21:55

Yes you do Smile | :)

Richard MacCutchan6-Oct-19 23:03

6-Oct-19 23:03

Interested to know how you can answer this, not so simple, issue, but struggle with the ones below, which are basic C.

Re: OT

_Flaviu6-Oct-19 23:32

6-Oct-19 23:32

I have never learn C, just c++ ... and this code where I am working on is written for Linux, and for other compilers than VS. That is why I got tones of errors, one of them I don't know how to handle them without broke the functionality (I cannot try what I modify, so I am working blind).

modified 7-Oct-19 8:30am.

Re: OT

Richard MacCutchan7-Oct-19 2:35

7-Oct-19 2:35

OT means "Off topic". I am replying to a message but discussing a different subject.

identifier 'mode_t'

_Flaviu6-Oct-19 8:08