ActiveX control container, I really need your help - C / C++ / MFC Discussion Boards

Rnd, Floor or Ceil from math.h is the way to go.

Christian Graus - Microsoft MVP - C++

There is no rnd in math.h.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

(int) (r+0.5f) is the way to go if you are rounding to the nearest integer with ?.5 always rounding up.

The second version avoids overflow problems. My question would be why would someone think adding 100000 would improve the rounding function. When dealing with floating point numbers, you really have to be careful when adding and subtracting values.

(NOTE: this only works for positive numbers, negative numbers must use -0.5f and not 0.5f)

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

-- modified at 10:26 Friday 9th September, 2005

Oh dear god, I just realized what they are doing.

(int) (f) does a truncation of the floating point number. In otherwords, it rounds to zero.

2.5 -> 2
0.3 -> 0
-4.5 -> -4

The "(int) (r+0.5f)" trick only works for positive values.

2.3 -> 2
2.7 -> 3
-0.2 -> 0
-0.7 -> 0 (WRONG - should be -1)

By doing 100000.5f, they AVOID (not remove) the negative problem.

Example, but we use 10.5f instead of 100000.5f

-0.2 + 10.5f = 10.3f -> 10 -> 0
-0.7 + 10.5f = 9.8f -> 9 -> -1

But dear god, WHAT A HACK.

The proper way of doing it is:

int i = (int) (r + (r > 0.0f ? 0.5f : -0.5f));

This is why Christian wants people to use math.h because it is easy to create things that sort of work, but often they don't always work.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

please, somebody could publish a simple example on SNMP in C++?

Thanks!

Sorry for my english

Search CP articles for SNMP. There are several examples.

"One must learn from the bite of the fire to leave it alone." - Native American Proverb

sebastianos wrote:
somebody could publish a simple example on SNMP in C++?

here is list :-
SNMP ARTICLE[^]

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV

Friends,
I want to develop a ActiveX control container,and save data in flat(uncompound) document.
My document CxxDoc is derived from COleDocument,and the constructor as following:
CxxDoc::CxxDoc()
{
// EnableCompoundFile();
// ^^^^^^^^^^^^^^^^^^^^^^^^^^I need a flat (uncompound) file.so i delete it.

...
}
Firstly, Is it OK????Can i save data in flat document?

Secondly,my client item is CxxClientItem,
class CxxClientItem : public COleClientItem

The WriteItem and ReadItem function (copied from the sample program of ActiceX control test container in Visual C++) as follows. They can work correctly in compound document. Please tell me how to change them from compound document to flat(uncompound) document. I'm a new and I really need your help. Laugh | :laugh:

void CxxClientItem::WriteItem( CArchive& ar )
{
USES_CONVERSION;
IStoragePtr pStorage;
IStreamPtr pStream;
IPersistStreamInitPtr pPSI;
TCHAR szItemName[64];
HRESULT hResult;
IPersistStoragePtr pPersistStorage;
CxxDoc* pDoc;
CLSID clsid;

(void)ar;

pDoc = GetDocument();
ASSERT_VALID( pDoc );
ASSERT( pDoc->m_lpRootStg != NULL );
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^It is wrong in uncompound document
ASSERT( pDoc->m_bCompoundFile );
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^It is wrong in uncompound document
ASSERT( m_lpStorage != NULL );
ASSERT( !ar.m_bForceFlat );

GetItemName( szItemName );

if( !pDoc->m_bSameAsLoad )
{
hResult = pDoc->m_lpRootStg->CreateStorage( T2COLE( szItemName ),STGM_CREATE|STGM_READWRITE|STGM_TRANSACTED|STGM_SHARE_EXCLUSIVE, 0, 0, &pStorage );
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^It is wrong in uncompound document
if( FAILED( hResult ) )
{
AfxThrowOleException( hResult );
}
m_lpNewStorage = pStorage;
m_lpNewStorage->AddRef();
m_bNeedCommit = TRUE;
}
else
{
pStorage = m_lpStorage;
}

......
}

void CxxClientItem::ReadItem( CArchive& ar )
{
USES_CONVERSION;
BOOL tUsedStream;
IStoragePtr pStorage;
IPersistStreamInitPtr pPSI;
IStreamPtr pStream;
TCHAR szItemName[64];
HRESULT hResult;
BOOL tQuickActivated;
IPersistStoragePtr pPersistStorage;
CLSID clsid;

(void)ar;

CxxDoc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
ASSERT(pDoc->m_lpRootStg != NULL);
// ^^^^^^^^^^^^^^^^^^^^^^^^^^It is wrong in uncompound document
ASSERT(pDoc->m_bCompoundFile);
// ^^^^^^^^^^^^^^^^^^^^^^^^^^It is wrong in uncompound document
ASSERT(m_lpStorage == NULL);
ASSERT(m_lpLockBytes == NULL);
ASSERT( !ar.m_bForceFlat );

// get item name
GetItemName( szItemName );

// open storage for this item
hResult = pDoc->m_lpRootStg->OpenStorage( T2COLE( szItemName ), NULL,
STGM_READWRITE|STGM_TRANSACTED|STGM_SHARE_EXCLUSIVE, 0, 0, &pStorage );
// ^^^^^^^^^^^^^^^^^^^^^^^^^^It is wrong in uncompound document
if( hResult != S_OK )
{
TRACE1( "Warning: unable to open child storage %s.\n", szItemName );
// upon failure throw file exception (item will be cleaned up)
AfxThrowOleException( hResult );
}
ASSERT(pStorage != NULL);

// remember the storage
m_lpStorage = pStorage;
ASSERT(m_lpStorage != NULL);
m_lpStorage->AddRef();

......
}

Hi folks,

how can I get the ascii code (0-255) from the wParam of the WM_KEYDOWN message (virtual-key code) ?

Thanks in advance,
Achim Klein