C / C++ / MFC

6-Jul-05 17:03

I have done some work recently in C#, integrating the product I work on with another project that exposes a COM object for this purpose. Now a third party has asked me to do the same in C++. This product in C# took an array of objects as a parameter, and returned an array of objects. The objects were strings. In C++, I've done this:

	const char * pClientFields[11] = {"CLIENT_RECD",<br />
						"CLIENT_FIRST",<br />
						"CLIENT_LAST",<br />
						"CLIENT_ADDRESS",<br />
						"CLIENT_CITY",<br />
						"CLIENT_STATE",<br />
						"CLIENT_ZIP",<br />
						"CLIENT_AREA",<br />
						"CLIENT_PHONE",<br />
						"CLIENT_BUSINESS",<br />
						"CLIENT_EMAIL"};<br />
<br />
	_variant_t * ClientFields = NULL;<br />
<br />
	_variant_t * GetClientFields()<br />
	{<br />
		if (ClientFields == NULL)<br />
		{<br />
			CComSafeArray<BSTR> array;<br />
			for(int i=0; i < 11; ++i)<br />
			{<br />
				array.Add(_bstr_t(pClientFields[i]));<br />
			}<br />
<br />
			VARIANT * pVar = new VARIANT();<br />
			pVar->vt = VT_ARRAY | VT_BSTR;<br />
			pVar->parray = array.Detach();<br />
<br />
			ClientFields = new _variant_t(pVar);<br />
		}<br />
<br />
		return ClientFields;<br />
	}

because the COM interface is expecting a _variant_t( and it returns one, too ). ClientFields at the end of this does not know what sort of variant it is, and so I get an exception. Can anyone please show me what I need to do here to get a _variant_t full of strings, and also how to read one at the other end ? I need it to compile in VC6 ( although the above is written in VC7 )

Christian Graus - Microsoft MVP - C++

Re: VARIANT/COM Hell

Jose Lamas Rios7-Jul-05 7:46

Jose Lamas Rios

7-Jul-05 7:46

Christian Graus wrote:
Can anyone please show me what I need to do here to get a _variant_t full of strings, and also how to read one at the other end ?

You can create the variant with something like this:

void BstrArrayFromWcharArray(VARIANT& var, WCHAR** pStrings, int size)
{
   var.vt = VT_ARRAY | VT_BSTR;
   var.parray = SafeArrayCreateVector(VT_BSTR, 0, size);
 
   for (long ix = 0; ix < size; ix++)
      SafeArrayPutElement( var.parray, &ix, ::SysAllocString(pStrings[ix]) );
}
 
WCHAR* pClientFields[] = 
{
   L"CLIENT_RECD",
   L"CLIENT_FIRST",
   L"CLIENT_LAST",
   L"CLIENT_ADDRESS",
   L"CLIENT_CITY",
   L"CLIENT_STATE",
   L"CLIENT_ZIP",
   L"CLIENT_AREA",
   L"CLIENT_PHONE",
   L"CLIENT_BUSINESS",
   L"CLIENT_EMAIL"
};
 
_variant_t ClientFields;
 
_variant_t* GetClientFields()
{
   if (ClientFields.vt == VT_EMPTY)
   {
      UINT size = sizeof(pClientFields)/sizeof(*pClientFields);
      BstrArrayFromWcharArray(ClientFields, pClientFields, size);
   }
 
   return &ClientFields;
}

You can access the elements of the array inside the variant with something like this:

void ShowBstrArray(const VARIANT var)
{
   if (var.vt != (VT_ARRAY | VT_BSTR))
      return;
 
   SAFEARRAY* psa = var.parray;
 
   for (long i = 0; i < (long)psa->rgsabound[0].cElements; i++)
   {
      BSTR bstr;
      SafeArrayGetElement(psa, &i, &bstr);
      CString s = bstr;
      AfxMessageBox(s);
   }
}
 
void Test()
{
   _variant_t* pFields = GetClientFields();
 
   ShowBstrArray(*pFields);
}

However, when accessing most or all of the elements in the array, the following alternatives, which make use of SafeArrayAccessData, are more efficient:

void BstrArrayFromWcharArray2(VARIANT& var, WCHAR** pStrings, UINT size)
{
   var.vt = VT_ARRAY | VT_BSTR;
   var.parray = SafeArrayCreateVector(VT_BSTR, 0, size);
 
   BSTR HUGEP* pbstr = NULL;
   if (FAILED(SafeArrayAccessData(var.parray, (void HUGEP**)&pbstr)))
      return;
 
   for (UINT ix = 0; ix < size; ix++)
      pbstr[ix] = ::SysAllocString(pStrings[ix]);
 
   SafeArrayUnaccessData(var.parray);
}
 
void ShowBstrArray2(const VARIANT var)
{
   if (var.vt != (VT_ARRAY | VT_BSTR))
      return;
 
   SAFEARRAY* psa = var.parray;
 
   BSTR HUGEP* pbstr = NULL;
   if (FAILED(SafeArrayAccessData(psa, (void HUGEP**)&pbstr)))
      return;
 
   for (UINT i = 0; i < psa->rgsabound[0].cElements; i++)
   {
      CString s = pbstr[i];
      AfxMessageBox(s);
   }
 
   SafeArrayUnaccessData(psa);
}

I tried it with VS6 and it seemed to work fine. Hope that helps,

--
jlr
http://jlamas.blogspot.com/[^]

Re: VARIANT/COM Hell

Christian Graus7-Jul-05 13:15

Howe to insert a number into a table in the Oracle by ADO

7-Jul-05 13:15

Wow - that's a lot of code, thanks for going to this effort for me.

Christian Graus - Microsoft MVP - C++

Re: VARIANT/COM Hell

Jose Lamas Rios7-Jul-05 15:49

Jose Lamas Rios

7-Jul-05 15:49

No problem. Glad to be of help.

--
jlr
http://jlamas.blogspot.com/[^]

zwzcode6-Jul-05 15:22

zwzcode

6-Jul-05 15:22

I create a table A in the Oracle.
CREATE TABLE A
(
ID NUMBER(7) primary key
);
Now ,I want to insert a reocrd in the table A;

_ConnectionPtr pConn=NULL;

pConn.CreateInstance(__uuidof(Connection));

_RecordsetPtr pRst=NULL;

pRst.CreateInstance(__uuidof(Recordset));

pConn->Provider="OraOLEDB.Oracle.1";

try
{
pConn->Open("","ISVISION","ISVISION",NULL);

pRst->CursorLocation=adUseClient;
pRst->Open("A",pConn.GetInterfacePtr(),adOpenStatic,adLockOptimistic,adCmdTable);

pRst->AddNew();
pRst->Fields->Item[0L]->Value=100L; //But it throw a excpetion here. I dont know the reason. If I alter the datatype of ID to CHAR(10),it is all right.
//这里就会出现异常，如果表A的ID的数据类型是CHAR(10)的，又不会出错？
pRst->Update();

pRst->Close();
pConn->Close();
}
catch (_com_error& e)
{
MessageBox(e.Description(),"error",MB_OK|MB_ICONWARNING);
return ;
}

if (pConn)
pConn.Release();
if (pRst)
pRst.Release();

HELP problem with CComboBox AddString recovery

cgb1436-Jul-05 14:06

cgb143

6-Jul-05 14:06

I am trying to maintain someone elses code and do not fully understand it's nuances. However I am trying to recover a string stored in a CComboBox list.

I posted this at little earlier at 19:50 but some of the code was missing/corrupted

//---------------------------------
void Control::DoDataExchange(CDataExchange* pDX)
{
Sheet* pSheet = ((C_App*)AfxGetApp())->getSheet();

MyPropertyPage::DoDataExchange(pDX);
//{{AFX_DATA_MAP(Control)
DDX_Control(pDX, IDC_OTHER_COMBO, m_otherCombo); // IDC_OTHER_COMBO is the CComboBox ID:
//}}AFX_DATA_MAP
}
//---------------------------------

//Sheet::PopulateOtherCombo()
{
int i;
int entry=0;
int index=0;
CString name;
for (i=0;i<maxcount;i++)
{

="" some="" code="" that="" constructs="" the="" string="" 'name'
=""

="" write="" 'name'="" to="" ccombobox
index="getControl()-">m_otherCombo.AddString(name);
if (index != CB_ERR)
{
getControl()->m_otherCombo.SetItemData(index, entry++);
}
}
}

//---------------------------------------------------------------------------
//So far I have built a list of strings stored sequentially by 'index' but how do I recover a string ??
// When I click on the CComboBox, the list opens and I can select any of the entries.

int index = getControl()->m_otherCombo.GetCurSel();

// Gets the index # of the currently selected CComboBox entry.
// Now I want to copy the text of the currently selected entry somewhere else.
// I have the index but there is no GetString(index) function

// HELP!

Thanks for any help you can offer

Charles

Christian Graus6-Jul-05 14:44

6-Jul-05 14:44

The code gets 'corrupted' because you didn't check the box that says 'Do not treat <'s as HTML tags'. Edit this post so we can see the code, then you may get a reply Smile | :)

Christian Graus - Microsoft MVP - C++

cgb1436-Jul-05 15:13

cgb143

6-Jul-05 15:13

new to the forum. I'll look for it next time. meanwhile Brad Bruce suggested GetLBText. thanks anyway

Brad Bruce6-Jul-05 14:59

Brad Bruce

6-Jul-05 14:59

Try GetLBText(...)

cgb1437-Jul-05 5:28

cgb143

7-Jul-05 5:28

Thqanks Brad

works great Smile | :)

Re: HELP CComboBox AddString and recovery

David Crow6-Jul-05 15:44

David Crow

6-Jul-05 15:44

If by 'recover' you mean get the currently selected item in the combobox, I use GetWindowText().

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

Anonymous6-Jul-05 13:54

Anonymous

6-Jul-05 13:54

sorry some code went missing when I pasted.. here it is again

void Control::DoDataExchange(CDataExchange* pDX)
{
Sheet* pSheet = ((C_App*)AfxGetApp())->getSheet();

MyPropertyPage::DoDataExchange(pDX);
//{{AFX_DATA_MAP(Control)
DDX_Control(pDX, IDC_OTHER_COMBO, m_otherCombo); // IDC_OTHER_COMBO is the CComboBox ID:
//}}AFX_DATA_MAP
}

//-----------------------------------------------------------------
Sheet::PopulateOtherCombo()
{
int i;
int entry=0;
int index=0;
CString name;
for (i=0;i<max_count;i++)
{

=""
="" some="" code="" that="" constructs="" the="" string="" 'name'
=""

="" write="" 'name'="" to="" ccombobox
="" index="getControl()-">m_otherCombo.AddString(name);
if (index != CB_ERR)
{
getControl()->m_otherCombo.SetItemData(index, entry++);
}
}
}

//---------------------------------------------------------------------------
//So far I have built a list of strings stored sequentially by 'index' but how do I recover a string ??
// When I click on the CComboBox, the list opens and I can select one of the entries

int index = getControl()->m_otherCombo.GetCurSel();

// Gets the index # of the currently selected CComboBox entry.
// Now I want to copy the text of the currently selected entry somewhere else.
// I have the index but there is no GetString(index) function

// HELP!

convert number to char

Ista6-Jul-05 12:42

Ista

6-Jul-05 12:42

what function would take

int i = 36;

to a char c?

I'm not an expert yet, but I play one at work. Yeah and here too.

markkuk6-Jul-05 13:06

markkuk

6-Jul-05 13:06

char c = i;

toxcct6-Jul-05 20:25

toxcct

6-Jul-05 20:25

as suggested, char c = (char)i; is correct but can cause a warning as you could lost some data.
char (which mean signed char) can contain values from -128 to +127, so any value of your int that is out of bound would be truncated...

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Bob Stanneveld6-Jul-05 20:58

Bob Stanneveld

6-Jul-05 20:58

toxcct wrote:
as suggested, char c = (char)i; is correct but can cause a warning as you could lost some data.
char (which mean signed char) can contain values from -128 to +127, so any value of your int that is out of bound would be truncated...

Since an int is 4 times the size of a char, the value will always be truncated! One way to make sure that your value has the same sign bit as the previous int variable is:

c = (i & 0x80000000) ? c | 0x80 : c & 0x7F

Here your test the sign bit i & 0x80000000. Depending on it is set, you set or remove the sign bit from the char.

Behind every great black man...
... is the police. - Conspiracy brother

Blog[^]

toxcct7-Jul-05 0:25

toxcct

7-Jul-05 0:25

when you copy a signed integer (either char, short, int or long), the sign bit is copied too...

so, making this will work without any data loss :

int i = -2;
char c = (char) i;
ASSERT(c == -2);

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Bob Stanneveld7-Jul-05 1:24

Bob Stanneveld

7-Jul-05 1:24

toxcct wrote:
when you copy a signed integer (either char, short, int or long), the sign bit is copied too...

I just verified it and shame on me...

Thanks for pointing that out!

Behind every great black man...
... is the police. - Conspiracy brother

Blog[^]

easy translation for c# .

dSolariuM6-Jul-05 21:11

dSolariuM

6-Jul-05 21:11

Hi,
You can Use ltoa function.
//////////////////////////
char ch[256];
ltoa(1234,ch,10);
//////////////////////////
cheers.

Message Box Position

tas28266-Jul-05 11:21

tas2826

6-Jul-05 11:21

I have a scenario where the size and position of a warning dialog is inconsistent depending on what is done with a modeless dialog that produces it. I have a modeless dialog that has a combo box that fires a kill focus event. If I tab out of the combo box the warning pops as expected centered over the parent modeless dialog centered both horizontally and vertically.

If I highlight the combo box, then click and drag the modeless dialog by its caption bar the kill focus fires as expected. However, the popup warning is now half the size and off to the left of the modeless dialog that produced it. It appears to be centered on the Windows desktop instead of my application dialog.

I have tried it as MessageBox, AfxMessageBox, and as a custom dialog we use for warnings and errors (Just a MessageBox with some custom bells and whistles). All produce the same weird positioning behavior.

Is this a quirk with MFC or Windows?

Is there any way for me to obtain a handle to a pop up dialog, such as AfxMessageBox and position it myself?

Is there some simple reason/solution I am just not seeing?

The app is written in VC++ 6. This is just an annoyance and does not effect the functionality of the app, it is just bugging me, help.

Thanks,

Troy

Ista6-Jul-05 11:07

Ista

6-Jul-05 11:07

Vector but I would to define a foreach statement

std::vector<cworddata*>::iterator itNum = this->_arrWords.begin();

for(; itNum < this->_arrWords.end();itNum++ )

how would I change it to said like so

foreach( myObject obj in this->_arrWords )

I know I would use a define but what else>

please help.
Nick

I'm not an expert yet, but I play one at work. Yeah and here too.

Re: easy translation for c# .

Christian Graus6-Jul-05 11:17