C / C++ / MFC

Re: Test my new hash algorithm

3-May-02 9:08

Take a look at CRC32. It is very good at detecting errors and works very well at detecting change. If you need even better change detection, MD5 works well.

Tim Smith

I know what you're thinking punk, you're thinking did he spell check this document? Well, to tell you the truth I kinda forgot myself in all this excitement. But being this here's CodeProject, the most powerful forums in the world and would blow your head clean off, you've got to ask yourself one question, Do I feel lucky? Well do ya punk?

Dominik Reichl3-May-02 9:12

Dominik Reichl

3-May-02 9:12

I know CRC32 and MD5 (and many more). But MD5 is a cryptographic hash function and it seems that my algorithm is at least as fast as CRC32 and when using longer hashes it seems to be more secure than CRC32. It seems that if increasing the hash size the speed doesn't slow down.

Have a look at the sample.

Re: Test my new hash algorithm

Tim Smith3-May-02 9:53

sorting ctreectrl's items

3-May-02 9:53

Ok, I have found many failures so far.

1. The following two data streams match (all bytes processed in one UFH_HashIn)

unsigned char szData1 [] = { 1, 0x80, 2, 3, 1,    0, 2, 3 };
unsigned char szData2 [] = { 1,    0, 2, 3, 1, 0x80, 2, 3 };

2. These two data streams match (all bytes processed in one UFH_HashIn)

unsigned char szData1 [] = { 0 };
unsigned char szData2 [] = { 0, 0 };

3. These two data stream match (all bytes processed in one UFH_HashIn). This is really a variant on #2.

unsigned char szData1 [] = { 1 };
unsigned char szData2 [] = { 1, 0 };

4. The routine is very depending on how a stream is processed. Given the following stream, if 5 bytes are processed followed by 3 to generate the first hash, and then all 8 bytes are processed to generate a new hash, the resulting values do not match. Thus giving you a false failure to match.

unsigned char szData1 [] = { 1, 0x80, 2, 3, 1,    0, 2, 3 };

Many of the problems you have are the exact problems that CRC-32 try to fix. Now even CRC32 can have a problem with test case #2 *IF* a value of 0 is used for the seed. But the other failures wouldn't happen with CRC32.

Tim Smith

I know what you're thinking punk, you're thinking did he spell check this document? Well, to tell you the truth I kinda forgot myself in all this excitement. But being this here's CodeProject, the most powerful forums in the world and would blow your head clean off, you've got to ask yourself one question, Do I feel lucky? Well do ya punk?

Standard Form prob!

Steven Richardson3-May-02 8:42

Steven Richardson

3-May-02 8:42

i am doing some very large calculations in a RichEdit and it keeps going into standard form like 546E10 is there a way to stop this?

P.S i am using Borland C++ 5 and oop

3-May-02 8:01

here is my code..
but in the callback function,two messageboxs contains empty string. do you know why?
when i insert an item to the tree, i had set item.lparam = info;
info is CString, which is .txt_2342_5/3/02 , type,size,and date combine in one stentence
i want to sort my tree by date, by size, and by type as window explore does.

any clue???

/*===============================================================================
Sorting a tree using CTreeCtrl::SortChildrenCB()

=================================================================================*/
CTreeCtrl *myTreeCtrl;
static int CALLBACK MyCompareProc(LPARAM lParam1, LPARAM lParam2, LPARAM lParamSort)
{
// lParamSort contains a pointer to the tree control.The lParam of an item is just its handle.
CTreeCtrl *pmyTreeCtrl = (CTreeCtrl*) lParamSort;
CString strItem1 = pmyTreeCtrl->GetItemText((HTREEITEM) lParam1);
CString strItem2 = pmyTreeCtrl->GetItemText((HTREEITEM) lParam2);
AfxMessageBox(strItem1);
AfxMessageBox(strItem2);
return strcmp(strItem2, strItem1);
}

//sorting trees
void CSMPprojectDlg::SortTreeItem()
{
// Sort the tree control's items using my callback procedure.
HTREEITEM hRoot = m_TreeCtrl.GetRootItem();
HTREEITEM hNextItem = m_TreeCtrl.GetNextItem(hRoot,1);
while( hNextItem != NULL )
{
m_TreeCtrl.SetItemData(hNextItem,(DWORD)hNextItem);
hNextItem = m_TreeCtrl.GetNextItem(hNextItem,1);
}

myTreeCtrl = &m_TreeCtrl;
TVSORTCB tvs;
tvs.hParent = m_TreeCtrl.GetRootItem();
tvs.lpfnCompare = MyCompareProc;
tvs.lParam = (LPARAM)myTreeCtrl;
m_TreeCtrl.SortChildrenCB(&tvs);
MessageBox("hello");

}

void CSMPprojectDlg::SortingAtree()
{
SortTreeItem();
}

repost: my math problem

lucy3-May-02 6:51

VStudio setting to see macro expansion?

3-May-02 6:51

here is the original code

void Compensate(float XCentroid, float ZCentroid, 
		float *CompensatedX, float *CompensatedZ)
{
    double Dr = 0.0;
    double LCentroidX = 0.0;
    double LCentroidZ = 0.0;
    double VectLength = 0.0;
    double FRACTION = 0.009835;
    double EXPONENT = 2.400;

    LCentroidX = (double)XCentroid;
    LCentroidZ = (double)ZCentroid;

    VectLength = sqrt( (pow(LCentroidX, 2.0)) + (pow(LCentroidZ, 2.0)) );

    Dr = FRACTION * ( pow(VectLength, EXPONENT) );

    if ( VectLength != (double)0.0 )
      {
        *CompensatedX = (float)LCentroidX + ( Dr * ( LCentroidX / VectLength ) );
        *CompensatedZ = (float)LCentroidZ + ( Dr * ( LCentroidZ / VectLength ) );
      }
    else
      {
	/* return original co-ordinates */
	*CompensatedX = XCentroid;
	*CompensatedZ = ZCentroid;
      }

    return;

} /* end Compensate */

so how can I reverse this algorithm? That is, based on CompensatedX and CompensatedZ, how can I get the original XCentroid and ZCentroid?

I tried the following, but it doesn't work.

CompensatedVect = sqrt(pow(CompensatedX, 2.0), pow(CompensatedZ, 2.0));
CompensatedDr = pow((CompensatedVect/FRACTION), 1/EXPONENT);

XCentroid = CompensatedX / (1 + CompensatedDr/CompensatedVect);
ZCentroid = CompensatedZ / (1 + CompensatedDr/CompensatedVect);

I hope I am posting it in the correct forum this time. Unsure | :~

hiseldl3-May-02 6:10

hiseldl

3-May-02 6:10

I wrote a #define macro and I would like to see the output
after it's preprocessed, is there a setting in VStudio
that would show the macro after it is expanded?

.dave.

David Hisel -- http://www.hisel.com/

Tom Archer3-May-02 6:36

3-May-02 6:36

From the Property Pages dialog:

Expand the Configuration folder
Expand the C/C++ folder
Click the Preprocessor item
Change the Generate Preprossed File to the desired setting (line numbers or not in the output file)

When you build the project, you will have preprocessed versions of your files with the .i extension.

Cheers,
Tom Archer
Author, Inside C#

A total abstainer is one who abstains from everything but abstention, and especially from inactivity in the affairs of others.

lucy3-May-02 6:55

3-May-02 6:55

sorry, but didn't find item 4 (line numbers or not). should I include some C++ macros there?

Tom Archer3-May-02 7:02

3-May-02 7:02

What do you see as options on the Preprocessor page? The third item should be labelled "Generate Preprocessed File". You click in that and drop the combo down to see the options.

Cheers,
Tom Archer
Author, Inside C#

A total abstainer is one who abstains from everything but abstention, and especially from inactivity in the affairs of others.

lucy3-May-02 7:11

3-May-02 7:11

I did a Project->Settings->C/C++ -> Category: Preprocessor, and what I see is:
Preprocessor definitions (edit box)
UnDefined symbols: (check box, followed by an edit box)
Additional include directories: (edit box)
Ignore standard include paths (check box).

What did I miss?

Tom Archer3-May-02 7:18

3-May-02 7:18

Oh. Are you running VS6? I'm running VS.NET.

If you're running VS6, what you need to know is the following:

Create preprocessor file - add /P to the CL call
Create preprocessor file (with line numbers) - add /EP and /P to the CL call

Therefore, either look through for the pages for this option or manually add it.

Cheers,
Tom Archer
Author, Inside C#

A total abstainer is one who abstains from everything but abstention, and especially from inactivity in the affairs of others.

lucy3-May-02 7:39

3-May-02 7:39

got it. Thank you, Tom.
In VS6, it's add /P or /EP (output is the output window of VS6) in Project Options of Project->Settings->C/C++ ->Category: Preprocessor.

Tom Archer3-May-02 10:08

3-May-02 10:08

No problem, Lucy. This is tremendously valuable in learning how those magic MFC and ATL macros work.

Cheers,
Tom Archer
Author, Inside C#

A total abstainer is one who abstains from everything but abstention, and especially from inactivity in the affairs of others.

hiseldl3-May-02 7:30

hiseldl

3-May-02 7:30

the Property Pages, do you mean Project->Settings from the main menu?

Also, I am using VStudio 6 Enterprise Edition, if that helps.

.dave.

David Hisel -- http://www.hisel.com/

Tom Archer3-May-02 7:35

3-May-02 7:35

Sorry. I use VS.NET and forget that most don't. Look at my response to Lucy where I explain (as well as I can withouut the VS6 environment installed) how to do this in VS6.

Cheers,
Tom Archer
Author, Inside C#

A total abstainer is one who abstains from everything but abstention, and especially from inactivity in the affairs of others.

Debug Assertion?

Aoife3-May-02 5:08

3-May-02 5:08

Hello,

In my MFC application I have two similar dialog boxes. Each have a List Control Box and each has a varaible (of type CListCtrl) associated to them. One of them works fine but I get a Debug Assertion error on the first of these four lines in the second dialog.

m_MyListControl2.InsertItem(0, Line1, 0)

m_MyListControl2.SetItemText(0, 1, Line2);
m_MyListControl2.SetItemText(0, 2, Line3);
m_MyListControl2.SetItemText(0, 3, Line5);

The dialog boxes all have the same header files and the contents of DoDataExchange() are similar too.

Does anyone know why this is happening?

Thanks,
Aoife

mystro_AKA_kokie3-May-02 5:17

mystro_AKA_kokie

3-May-02 5:17

if you didn't make those calls in OnInitDialog then it's because they haven't been created yet.

Aoife3-May-02 5:31

3-May-02 5:31

But the first dialog box isn't mentioned in OnInitDialog and it works fine. Could it be because there is two of them?

Thanks,

Tim Smith3-May-02 5:30

3-May-02 5:30

What does the debug assertion say. Not only does it usually print text about why it asserted, but if you look at the source code where the assert was raise, it sometimes gives you information about what you need to do to correct the problem.

Tim Smith

I know what you're thinking punk, you're thinking did he spell check this document? Well, to tell you the truth I kinda forgot myself in all this excitement. But being this here's CodeProject, the most powerful forums in the world and would blow your head clean off, you've got to ask yourself one question, Do I feel lucky? Well do ya punk?

Aoife3-May-02 5:55

3-May-02 5:55

It says that the "Debug Assertion Failed" in file winctrl.cpp at line 547.

void CListCtrl::DrawItem(LPDRAWITEMSTRUCT)
{
ASSERT(FALSE);
}

This is a MFC\src file.
It gives no other reason as to why its happening.

Thanks

Tim Smith3-May-02 6:10

3-May-02 6:10

Then it looks like your list control is marked as owner drawn but you aren't handling the DrawItem routine to draw it.

Tim Smith

I know what you're thinking punk, you're thinking did he spell check this document? Well, to tell you the truth I kinda forgot myself in all this excitement. But being this here's CodeProject, the most powerful forums in the world and would blow your head clean off, you've got to ask yourself one question, Do I feel lucky? Well do ya punk?

Aoife3-May-02 6:29