conversion problem - C / C++ / MFC Discussion Boards

vicky000001-Jan-09 17:45

1-Jan-09 17:45

Thnks for your replay...
i already used? My question is how to avoid the image appended with check box in first column....?

Access Violation 0xC0000005

whiteclouds31-Dec-08 18:14

whiteclouds

31-Dec-08 18:14

Hi all!
I'm developing an console application with MFC support. Now I meet an exception when I execute the following code:

    CBitmap 	*bitmap;
    CDC 		memDC;
    CRect		rect;
    CWnd *pWnd=m_pWndHide;//->GetWindow(GW_HWNDFIRST);
//    CWindowDC	dc(pWnd);

    memDC.CreateCompatibleDC(&m_hDC);//(&dc);

    // Calculate required height from specified width
    int height = CAH_glo_y * width / CAH_glo_x;

	bitmap = new CBitmap();
    //The next line will occur "Access Violation 0xC0000005"
    bitmap->CreateCompatibleBitmap(&m_hDC, width, height );//(&dc, width, height );
    CBitmap* pOldBitmap = memDC.SelectObject(bitmap);
    // using the current background colour (assume white for the moment)
    memDC.PatBlt(0, 0, width,height, WHITENESS);
    ...

I trace this error into a source file named SBHEAP.c in MFC then. The function stopped in is __sbh_alloc_block. The related code is following:

...
pEntry->pEntryNext = pHead->pEntryNext;
pEntry->pEntryPrev = pHead;
pHead->pEntryNext = pEntry;
pEntry->pEntryNext->pEntryPrev = pEntry;//Stop here
...

I watch the value of pHead->pEntryNext . It is NULL. So I can't access it. But I don't know why and how to resolve it. Confused | :confused:

This code will be executed many times before. But it is wrong when the 3 times. If someone can tell me or give me some good advice, I will be very glad. Thanks!

Regards

whiteclouds

Re: Access Violation 0xC0000005

Nibu babu thomas31-Dec-08 23:16

Nibu babu thomas

31-Dec-08 23:16

whiteclouds wrote:
bitmap->CreateCompatibleBitmap(&m_hDC, width, height );//(&dc, width, height );

Note that if width and height is too big then CreateCompatibleBitmap does fail. Also how did you get m_hDC. Is this a valid DC?

Nibu babu thomas
Microsoft MVP for VC++

Code must be written to be read, not by the compiler, but by another human being.

Programming Blog: http://nibuthomas.wordpress.com

Re: Access Violation 0xC0000005

whiteclouds1-Jan-09 12:46

whiteclouds

1-Jan-09 12:46

Hi, thomas!
Thanks for your reply.
I think I had found the reason. After I delete some variables that aren't be used any more, the exception is missing. But another exception is occur same as this when I use the code following:

time_t  ltime;      // local time
struct  tm  *gmt;   // Greenwich Mean Time
png_time    ttime;  // png format

time (&ltime);  // get the local time---EXCEPTION 0xC0000005 OCCUR HERE!
gmt = gmtime (&ltime);  // convert to gmt
png_convert_from_struct_tm (&ttime, gmt);  // convert to png format
png_set_tIME (png_ptr, info_ptr, &ttime);

I trace this exception into MFC and I found when a function named _mlock was invoked in the __tzset function, the exception occur. The related code like this:

_mlock( _TIME_LOCK );

I don't know the reason and hope you or others can give me some suggestion. Thank you!

Regards!

whiteclouds

processor affinity

RomTibi31-Dec-08 13:49

RomTibi

31-Dec-08 13:49

How can I assign to a certain processor a process?
Can I list the processes assigned to a certain processor?

If possible, in VC++6 Wink | ;)

36. When you surround an army, leave an outlet free.
...
Do not press a desperate foe too hard.

SUN-TZU - Art of War

Re: processor affinity

Mark Salsbery31-Dec-08 15:22

Mark Salsbery

31-Dec-08 15:22

RomTibi wrote:
How can I assign to a certain processor a process?

You can assign a process to selected processor(s) with SetProcessAffinityMask().

RomTibi wrote:
Can I list the processes assigned to a certain processor?

You could enumerate the current processes and check which processors each
is set to use, perhaps using these functions:

EnumProcesses()
OpenProcess()
GetProcessAffinityMask()
CloseHandle()

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: processor affinity

RomTibi1-Jan-09 2:55

RomTibi

1-Jan-09 2:55

Thanks a lot! Smile | :)

36. When you surround an army, leave an outlet free.
...
Do not press a desperate foe too hard.

SUN-TZU - Art of War

conversion problem

wubousc31-Dec-08 10:17

wubousc

31-Dec-08 10:17

Hi,

Could someone please let me know why my code can not pass compilation? (VC++9.0,vista 64-bit)

The problems happens in the "<<" operator overload function. It seems my code can not pass some constness check.

#include <map>
#include <vector>
#include <iterator>
#include <algorithm>
#include <iostream>

using namespace std;

typedef pair<string,int> pairSI;

struct StringToSIPair
{
explicit StringToSIPair(int val) { intVal = val; }

pairSI operator () (string str)
{
pairSI psi = make_pair(str, intVal);
return psi;
}

int intVal;
};

void VecToMap(vector<string> &vecStr, int iniVal, map<string,int> &siMap)
{
transform(vecStr.begin(), vecStr.end(), inserter(siMap, siMap.begin()), StringToSIPair(iniVal));
}

ostream & operator << (ostream &out, map<string, int> &siMap)
{
for(map<string, int>::iterator it = siMap.begin(); it != siMap.end(); ++it)
{
out<<"key: "<<it->first<<" value: "<<it->second<<endl; // the compiler said there is a conversion problem
}

return out;
}

int main()
{
map<string,int> siMap;
vector<string> strVec;

strVec.push_back("bob");
strVec.push_back("alex");
strVec.push_back("alal");

VecToMap(strVec, 4, siMap);

cout<<siMap<<endl;

return 0;
}

regards,
Bob

Re: conversion problem

Rick York31-Dec-08 11:47

Rick York

31-Dec-08 11:47

First, I would recommend defining a type for your map. Something like :

typedef map<string,int> StringIntMap;

This could simplify some of the code.

Second, try using some temporary variables of the correct type to save the values of the first and second members of the iterator and then use those temps for the output. That should show you exactly what the compiler is expecting for variable types and allow you to cast if and as needed.

Re: conversion problem

wubousc31-Dec-08 13:32

wubousc

31-Dec-08 13:32

Hi, Rick,

Do you mean I should change the code like this?

ostream & operator << (ostream &out, map<string,> &siMap)
{
  for(map<string,>::iterator it = siMap.begin(); it != siMap.end(); ++it)
  {
string key = it->first;
int value = it->second;
out<<"key: "<<key<<" value: "<<value<<endl;
  }

  return out;
}

However, it doesn't fix the problem. I am confused because I think ostream has the ability to output string no matter it is const or not.

regards,
Bob

How to separate a specified number of Bits from a DWORD?

Joseph Marzbani31-Dec-08 8:16

Joseph Marzbani

31-Dec-08 8:16

Suppose we have a number of type DWORD and we want to extract four 6-bit number and a byte from it. Some thing like this:

(DWORD) ---> 10100101101000110100011010101001

(Result) ---> 101001 011010 001101 000110 10101001

If you want to introduce me 'Bit Field Operators', be aware! It does NOT work in this manner.

Thank you masters!

Re: How to separate a specified number of Bits from a DWORD?

harold aptroot31-Dec-08 8:25

harold aptroot

31-Dec-08 8:25

Just shift and mask it?
the byte: dword & 0xFF
last 6bit value: (dword >> 8) & 0x3F
next 6bit value: (dword >> 14) & 0x3F
etc?

Would that work?

Re: How to separate a specified number of Bits from a DWORD?

Jijo.Raj31-Dec-08 11:54

Jijo.Raj

31-Dec-08 11:54

Possibly another approach is to use union. Just check the following code snippet.

// Disable the packing.
#pragma pack(1)

// Use the union to access bytes of DWORD.
union DWordParser
{
    DWORD DwordValue;
    BYTE Bytes[4];
};

// Using the parser.
DWordParser Parser;
Parser.DwordValue = 255;

// Now get 6 bits of 3ed byte.
BYTE ThirdByte = Parser.Bytes[2] & 0x3F;

But you have to sacrifice performance for readability. Wink | ;)

Regards,
Jijo.

_____________________________________________________

http://weseetips.com[^] Visual C++ tips and tricks. Updated daily.

Re: How to separate a specified number of Bits from a DWORD?

krmed31-Dec-08 14:12

krmed

31-Dec-08 14:12

Can you explain why you feel that bit fields won't work for you?

Karl - WK5M
PP-ASEL-IA (N43CS)
PGP Key: 0xDB02E193
PGP Key Fingerprint: 8F06 5A2E 2735 892B 821C 871A 0411 94EA DB02 E193

Re: How to separate a specified number of Bits from a DWORD?

Richard Andrew x641-Jan-09 6:52

Richard Andrew x64

1-Jan-09 6:52

krmed wrote:
Can you explain why you feel that bit fields won't work for you?

I'm guessing it's because he didn't know how to use them properly. Poke tongue | ;-P

Stuck in ShowWindow

dj440031-Dec-08 4:41

dj4400

31-Dec-08 4:41

Hi all,
I have a multithreaded application written in c++ vs6.
I try to create a new dialog within an existing dialog in that application and when i call
ShowWindow(SW_SHOW)for the new dialog it doesnt do anything.
If i put a break point there, it seems that it stops in the call to ShowWindow and doesnt continue the execution.
Can someone explain this strange behavior and suggest a way to overcome this problem?
Thanks
Simon.

Re: Stuck in ShowWindow

Mark Salsbery31-Dec-08 6:13

Mark Salsbery

31-Dec-08 6:13

All these dialogs are created on the same thread?

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Stuck in ShowWindow

led mike31-Dec-08 7:20

led mike

31-Dec-08 7:20

Mark Salsbery wrote:
All these dialogs are created on the same thread?

ddd_shocron wrote:
I try to create a new dialog within an existing dialog

Doesn't that tell you exactly what is being done? It's created within Laugh | :laugh:

led mike

Re: Stuck in ShowWindow

Mark Salsbery31-Dec-08 7:24

Mark Salsbery

31-Dec-08 7:24

led mike wrote:
Doesn't that tell you exactly what is being done?

I know it should, but I'm not so bright...

Poke tongue | ;-P

(early) Happy New Year! Beer | [beer]

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Stuck in ShowWindow [modified]

dj440031-Dec-08 20:48

dj4400

31-Dec-08 20:48

yes all these dialogs are created in the same thread.

To be more precise i call the create function for that dialog in the ctor of the containing dialog
and i call the ShowWindow(SW_SHOW) from within the OnInitDialog ,just before
i return true for the OnInitDialog.

Sigh | :sigh:

dj4400 formerly known as ddd_shocron

modified on Thursday, January 1, 2009 3:14 AM

Re: Stuck in ShowWindow

Mark Salsbery1-Jan-09 6:27

Mark Salsbery

1-Jan-09 6:27

dj4400 wrote:
i call the create function for that dialog in the ctor of the containing dialog

If the containing dialog is used as the parent for the created dialog,
then that may not work - the parent dialog window (HWND) hasn't been created yet
at that point.

Try calling create for the child dialog in the parent's OnInitDialog() (after calling
the base class' OnInitDialog()).

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Stuck in ShowWindow

dj44003-Jan-09 23:06

dj4400

3-Jan-09 23:06

Thanks Mark, you are right - i called the create function in the OnInitDialog and then it worked properly.
Smile | :)

how to solve the following problem?

zhiyuan1631-Dec-08 4:12

zhiyuan16

31-Dec-08 4:12

dear all

any problem? i couldn't find. thanks a lot

void CMeiTengDlg::OnPause() 
{
	// TODO: Add your control notification handler code here
	if(Pause)
	{
		m_Pause.SetWindowText("Pause");
		MCIWndResume(m_Video);
		Pause = FALSE;
	}
	else
	{
		m_Pause.SetWindowText("UnPause");
		MCIWndPause(m_Video);
		Pause = TRUE;
	}
}

void CMeiTengDlg::OnBrowse() 
{
	// TODO: Add your control notification handler code here
	m_Video = NULL;
	if(m_Video == NULL)
	{
		CFileDialog avi(TRUE,NULL,NULL,OFN_HIDEREADONLY,"MP3 Files (*.mp3)|*.mp3|AVI Files(*.avi)|*.avi|");
		if(avi.DoModal() == IDOK)
		{
			m_Path = avi.GetPathName();
			UpdateData(FALSE);
			
		}
	}
	
}

the resilt of compiling:

MeiTengDLg.cpp
.\MeiTengDLg.cpp(235) : error C2664: 'CWnd::SetWindowTextW' : cannot convert parameter 1 from 'const char [6]' to 'LPCTSTR'
        Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
.\MeiTengDLg.cpp(241) : error C2664: 'CWnd::SetWindowTextW' : cannot convert parameter 1 from 'const char [8]' to 'LPCTSTR'
        Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
.\MeiTengDLg.cpp(277) : error C2664: 'CFileDialog::CFileDialog(BOOL,LPCTSTR,LPCTSTR,DWORD,LPCTSTR,CWnd *,DWORD,BOOL)' : cannot convert parameter 5 from 'const char [48]' to 'LPCTSTR'
        Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
Build log was saved at "file://c:\Documents and Settings\ZhiYuan Li\Desktop\MeiTeng\MeiTeng\Release\BuildLog.htm"
MeiTeng - 3 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Re: how to solve the following problem?

Jijo.Raj31-Dec-08 4:27

Jijo.Raj

31-Dec-08 4:27

I think you've enabled unicode in your project settings. Enclose all your strings inside _T() macro like as follows, so that they will switch accordingly to either ansi or unicode strings.

m_Pause.SetWindowText( _T("Pause") );

Regards,
Jijo.

_____________________________________________________

http://weseetips.com[^] Visual C++ tips and tricks. Updated daily.

Removing Command bar controls of Excel-2007 in c++

SRKSHOME31-Dec-08 1:39

SRKSHOME

31-Dec-08 1:39

Hi,
How to delete command bar controls of excel in c++?
I know when we automate excel, there is a functin GetCommandBars().
I dont know how to use this? Anyone has idea?

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