Base pointer Blues!!! - C / C++ / MFC Discussion Boards

Renjith Ramachandran18-Dec-04 6:32

18-Dec-04 6:32

put the exe file name in project>Settings>Debug (executable for debug section)

Ninety-eight percent of the thrill comes from knowing that the thing you designed works, and works almost the way you expected it would. If that happens, part of you is in that machine.

E_INVALIDARG with EnvDTE::Commands::AddNamedCommand

Franz Klein17-Dec-04 20:58

Franz Klein

17-Dec-04 20:58

I am always getting a return value of E_INVALIDARG when the function AddNamedCommand is called: Cry | :((

CComPtr<envdte::command> pCreatedCommand;

hr = pCommands->AddNamedCommand(m_pAddInInstance, CComBSTR(commandname), CComBSTR(commandtext), CComBSTR(tb_name), VARIANT_FALSE, IDB_LOGO, NULL, EnvDTE::vsCommandStatusSupported+EnvDTE::vsCommandStatusEnabled, &pCreatedCommand);

IDB_LOGO is a 16x16 Bitmap.

I am using Visual Studio .NET 2003 on Win XP SP2. I have looked at the documentation and at other examples but I can't find where I am going wrong.

Any ideas?

I am the handsome one in the crowd.

special folder

zpc_93017-Dec-04 19:05

zpc_930

17-Dec-04 19:05

Hi Anybody know the property of special folder (such as Downloaded Program Files,Offline Web Pages )which We can not paste folder and file in such folder?

CSliderCtrl Problem

Fayez El-Far17-Dec-04 15:47

Fayez El-Far

17-Dec-04 15:47

I have a slider bar that determines a position in a synchronization thread. The thread accesses tonnes of linked lists, and on-disk files. Whenever the user drags the slider bar I get exceptions because the updates to the thread are too fast. I need a way to determine when the dragging has stopped, so I can only update the thread with the final slider position.
URGENT HELP NEEDED!

Fayez

Re: CSliderCtrl Problem

Ravi Bhavnani17-Dec-04 16:43

Ravi Bhavnani

17-Dec-04 16:43

I think you need to handle the notification for TB_THUMBPOSITION instead of TB_THUMBTRACK. In the interests of user friendliness, you should also handle notifications for TB_PAGEDOWN, TB_PAGEUP, etc.

/ravi

My new year's resolution: 2048 x 1536
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Re: CSliderCtrl Problem

Member 148659417-Dec-04 18:25

Member 1486594

17-Dec-04 18:25

I am currently using ON_WM_HSCROLL.
Can you direct me to the message handler functions for TB_THUMBPOSITION

Re: CSliderCtrl Problem

PJ Arends17-Dec-04 18:53

PJ Arends

17-Dec-04 18:53

SB_THUMBPOSITION is a possible value passed in the low word of the wParam parameter of the WM_HSCROLL message. In MFC it is the nSBCode parameter of the OnHScroll handler.

"You're obviously a superstar." - Christian Graus about me - 12 Feb '03

"Obviously ??? You're definitely a superstar!!!" mYkel - 21 Jun '04

Within you lies the power for good - Use it!

Base pointer Blues!!!

avenger_sb2517-Dec-04 14:13

avenger_sb25

17-Dec-04 14:13

Suppose i have a set up like this:

class Base 
 { 
 public: 
   int x; 
   virtual void f() 
 };
class Derv:public Base
 {
 public:
   int y;
   void f();
};

void main()
{
	Base *p;
	p=new Derv[4];

       //I WANT TO ACCESS EACH ENTRY OF THE ALLOCATED ARRAY USING POINTER OF BASE
       for(int i=0;i<4;i++)
          (p+i)->y=10;  //THIS CRASHES WHEN i>0 AS I HAVE EXPLAINED BELOW
   
        delete[]p;
}

NOW HERE IS THE PROBLEM-
I can access the first element using pointer 'p' BUT if i try to acces the second element of the array by doing p+1, MY PROGRAM CRASHES...

This is the problem:
Suppose the derived class array was allocated at 0x00000000, then p contains 0x11111111. I thought that p+1 will be 0x11111111+sizeof(Derv), BUT it is 0x11111111+sizeof(Base)

SO WHAT I WANT TO KNOW FORM YOU FRIENDS IS - HOW TO ACCESS THE ELEMENTS OF A DERIVED CLASS ARRAY USING BASE CLASS POINTER ???

thanx for ur time

...Avenger

Remember... testing & debugging are always part of programming ...so exterminate those stinking bugs

Re: Base pointer Blues!!!

Member 58088117-Dec-04 18:40

Member 580881

17-Dec-04 18:40

Hey Avenger,

Here's a funny workaround...

DWORD dw = (DWORD) p; // move in the array using this
Base* p2 = NULL;

for(int i=0;i<4;i++)
{
p2 = (Base*) dw;
p2->y=10;
dw += sizeof(Derv); // move to the next elem
}

What do you think??
Big Grin | :-D

Clinton

Re: Base pointer Blues!!!

avenger_sb2518-Dec-04 1:03

avenger_sb25

18-Dec-04 1:03

Nice trying Clinton! Big Grin | :-D

If you come up with a better solution, do let me know

chao! Rose | [Rose]

...Avenger

Remember... testing & debugging are always part of programming ...so exterminate those stinking bugs

Re: Base pointer Blues!!!

toxcct17-Dec-04 23:12

toxcct

17-Dec-04 23:12

hey, looking your code, i cannot see any inheritence between your two classes.

you must tell that Derv is derived from Base (public, protected or private as you like...) :

<font color=#0000FF>class </font>Base {
  <font color=#0000FF>public</font>:
    <font color=#0000FF>int </font>x;
    <font color=#0000FF>virtual void </font>f();
};

<font color=#0000FF>class </font>Derv : public Base {
  <font color=#0000FF>public</font>:
    <font color=#0000FF>int </font>y;
    <font color=#0000FF>void </font>f();
};

avenger_sb25 wrote:
Suppose the derived class array was allocated at 0x00000000

impossible, nothing can be allocated at the address 0x00000000 (and even the operating system don't !). you must test if the address returned by new is different from NULL ((void*)0x00000000) :

Base* p;
p = <font color=#0000FF>new </font>Derv[4];
<font color=#0000FF>if </font>(p != NULL) {
    <font color=#0000FF>for</font> (<font color=#0000FF>int </font>i = 0; i < 4; i++) {
        p[i]->y = 10;
    }
    <font color=#0000FF>delete</font>[] p;
}

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

this == 0x00000000

Gurra_Koo17-Dec-04 12:08

Gurra_Koo

17-Dec-04 12:08

Hi,

I'm debugging one of my mfc programms. I'm using a ON_COMMAND map thing to respond to a popup menu command...

When i´m debugging this function the debugger tells me that this is 0x00000000....
This cause a lot of trouble... And it seems that this is changing from time to time...
Sometimes it's a pointer to an array, sometimes something else...

I find this really wierd...

Re: this == 0x00000000

John R. Shaw17-Dec-04 13:04

John R. Shaw

17-Dec-04 13:04

Sounds like you are some how calling a class member function when the class no longer exist in memory. Which is the only time this should be NULL. Why it would ever be pointing to any thing else is anouther question.

INTP
"The more help VB provides VB programmers, the more miserable your life as a C++ programmer becomes."
Andrew W. Troelsen

Re: this == 0x00000000

17-Dec-04 18:32

I concur with John's statement.

As for your question of "pointing to something else", I've found the best solution is initialising every single pointer you use. It might seem a bit tedious with a "CMyClass* ptr = NULL;" line in every place, but at least it prevents debugging headaches! Cool | :cool:

Clinton

Re: this == 0x00000000

Gurra_Koo17-Dec-04 21:35

Gurra_Koo

17-Dec-04 21:35

It's just that the class member i'm calling does still exist in memory.
The function is a member of a CView-derrived class. And the view still exixsts!

And sometimes i can use the data members of the class in a proper way. And when i debug the code
this is changing!

Re: this == 0x00000000

Member 58088117-Dec-04 22:06

Member 580881

17-Dec-04 22:06

WOW!

That's some bug...

Hmm, lets see... if after this "change" occurs once and you cannot access your members properly thereafter, it could mean some copy function is playing foul and overwriting its buffer,...

but, if you can access your members correctly "now-and-then", well... all I can think of... is a pointer-to-view pointing to the wrong place...

Clinton

Getting the HWND from Filename

RedDragon2k17-Dec-04 11:12

RedDragon2k

17-Dec-04 11:12

Hi Guys

I have a problem(why else should i post here?). I only now the executable's name and it is sure that it is running. How can i get the HWND by just knowing the name of the file ?
Please Help !! Confused | :confused:

MFG
RedDragon2kx

Unix and C are the ultimate computer viruses.

Re: Getting the HWND from Filename

Sujan Christo17-Dec-04 17:03

Sujan Christo

17-Dec-04 17:03

Hi,
You can use the SPY++ Utility which comes with Visual Studio Tools
Sujan

Re: Getting the HWND from Filename

ThatsAlok17-Dec-04 17:15

ThatsAlok

17-Dec-04 17:15

RedDragon2k wrote:
have a problem(why else should i post here?). I only now the executable's name and it is sure that it is running. How can i get the HWND by just knowing the name of the file ?

Here Are the apis that will help you Out

->GetModuleHandle
->GetModuleHandleEx

-----------------------------
"I Think this Will Help"
-----------------------------
Alok Gupta
visit me at http://www.thisisalok.tk

Re: Getting the HWND from Filename

RedDragon2k17-Dec-04 21:28

RedDragon2k

17-Dec-04 21:28

Thanks a lot !!! D'Oh! | :doh:

;)

Unix and C are the ultimate computer viruses.

Visit me: www.programming.info.ms

Does anyone see a leak in this function?

Turtle Hand17-Dec-04 10:40

Turtle Hand

17-Dec-04 10:40

WinDbg and Microsoft support believe there is a memory leak in this function. I don't see it, but I'm not a guru. Can you see it?

void CClientSession::WriteTableListGetQueryListRS(
BOOL bDetails,
CString strTable,
enum eTable tableSave,
BOOL & bDeniedAccess,
BOOL & bDeniedAccessOther,
CStringArray & arrFields,
CArray<long, long=""> & arrLookups,
long & lLookup,
long & lPrimarySortField,
CString & strPrimarySortField,
CString & strPrimarySortOrder,
CString & strFields,
CString & strJoin,
CString & strWhere,
CString & strSQL)
{
CString strField;
CString strListFields;
CString strOrderBy;

TRY
{
if (bDetails && !m_pExt->GetServerPtr()->GetDeptView(strTable, m_lDeptID))
return NULL;

bDeniedAccess = m_pExt->GetServerPtr()->GetTableAccess(strTable, FALSE,
m_stateCurrent.m_strMainTable, m_stateCurrent.m_lMainRecord,
m_stateCurrent.m_strDepTable, m_stateCurrent.m_lDepRecord,
m_lDeptID, m_lCompanyID);

if (GetFunc() == CMD_SUMMARY)
bDeniedAccessOther = m_pExt->GetServerPtr()->GetTableAccess(strTable, FALSE,
m_stateCurrent.m_strMainTable, m_stateCurrent.m_lMainRecord,
"", -1, m_lDeptID, m_lCompanyID);
else if (bDeniedAccess)
return NULL;

if (bDeniedAccessOther)
return NULL;

// strFields i.e.: Person.Last_Name, Statuses.Company_ID, etc.
int nFind = strPrimarySortField.Find('.');
strPrimarySortField = strPrimarySortField.Mid(nFind + 1);
if (m_pExt->GetServerPtr()->GetDependencyCount(m_stateCurrent.m_strMainTable))
m_stateCurrent.m_strDepTable = m_pExt->GetServerPtr()->GetDependency(m_stateCurrent.m_strMainTable, 0);

if (!bDetails)
{
if (strTable == m_stateCurrent.m_strMainTable && !m_stateCurrent.m_strDepTable.IsEmpty())
{
if (strJoin.Find(" LEFT OUTER JOIN " + m_stateCurrent.m_strDepTable) == -1)
{
strJoin = " LEFT OUTER JOIN " + m_stateCurrent.m_strDepTable + " ON " + m_stateCurrent.m_strDepTable + "." + m_stateCurrent.m_strMainTable + "_ID=" + m_stateCurrent.m_strMainTable + ".ID" + strJoin;
strFields = m_stateCurrent.m_strDepTable + ".ID," + strFields;
}
}
else if (m_stateCurrent.m_eTable == Sub)
{
strJoin = " INNER JOIN Statuses ON Statuses.ID = " + strTable + ".Person_IDS";
}

//Add to SELECT fields
strFields = "," + strFields + GetSQLFields(strTable);

// Search Fields
if (GetFunc() == CMD_SEARCH)
{
CString strSearchField;
if (!GetCookie(GetTable() + ".SearchText").IsEmpty())
{
strSearchField = GetCookie(m_stateCurrent.m_strMainTable + ".SearchField");
if (strFields.Find("," + strSearchField + ",") == -1)
if (strFields.Find(strSearchField, strFields.GetLength() - strSearchField.GetLength()) == -1)
strFields += "," + strSearchField;
}
if (!GetCookie(GetTable() + ".SearchText2").IsEmpty())
{
strSearchField = GetCookie(m_stateCurrent.m_strMainTable + ".SearchField2");
if (strFields.Find("," + strSearchField + ",") == -1)
if (strFields.Find(strSearchField, strFields.GetLength() - strSearchField.GetLength()) == -1)
strFields += "," + strSearchField;
}
strSearchField.Empty();
}

//Build Sort Order
CString strColumn;
for(int nColumn = 0 ; nColumn < 3 ; nColumn++)
{
strColumn.Format("%s.Sort%d", strTable, nColumn);
strColumn = GetCookie(strColumn);
nFind = strColumn.Find('.');
if (nFind != -1)
strColumn = strColumn.Mid(nFind + 1);
if (!strColumn.IsEmpty())
if (strOrderBy.Find(strColumn) == -1)
AddSortColumn(strTable, strColumn, strOrderBy);
}

//Build Sort Order part 2
if (strOrderBy.IsEmpty())
{
CString strOrder = m_pExt->GetServerPtr()->GetDefaultOrderBy(strTable) + ",";
CString strSort;
nFind = strOrder.FindOneOf(", ");
nColumn = 0;
while (nFind != -1)
{
strOrderBy += strTable + "." + strOrder.Left(nFind);

if (strOrder[nFind] == ' ')
nFind = strOrder.Find(',');
strOrder = strOrder.Mid(nFind + 1);
nFind = strOrder.FindOneOf(", ");
if (nFind != -1)
strOrderBy += ',';
}
strOrder.Empty();
strSort.Empty();
}

CString strTableField;
strFields += ",";
strFields = strFields.Mid(1);
int nDot;
long lField = 0;

/*
strListFields
*/
nFind = strFields.Find(',');
while (nFind != -1)
{
strTableField = strFields.Left(nFind);
nDot = strTableField.Find('.');
if (nDot != -1)
{
strField = strTableField.Mid(nDot + 1);
strTableField.ReleaseBuffer(nDot);
}
else
{
strField = strTableField;
strTableField = strTable;
}
strFields = strFields.Mid(nFind + 1);

lLookup = m_pExt->GetServerPtr()->GetLookup(strTableField, strField);
arrLookups.Add(lLookup);
arrFields.Add(strField);

strTableField = AddFieldSQL(lLookup, lField, strJoin, strWhere, strOrderBy);

//Only display columns that aren't set to hidden in TableFields.Dept_Visible
if (m_pExt->GetServerPtr()->GetLookupHiddenView(lLookup, m_lDeptID) == FALSE)
{
if (!strListFields.IsEmpty())
strListFields += ",";
strListFields += strTableField;
}

if (lPrimarySortField == -1
&& m_pExt->GetServerPtr()->GetLookupTable(lLookup) + "." + strField == strPrimarySortField)
{
lPrimarySortField = lField;
strPrimarySortField = strTableField;
}

lField++;

nFind = strFields.Find(',');
}
strColumn.Empty();
strTableField.Empty();
}
else
strListFields = "COUNT(ID)";

strSQL = "SELECT " + strListFields + " FROM " + strTable + strJoin + strWhere;
if (!strOrderBy.IsEmpty())
strSQL += " ORDER BY " + strOrderBy;
OutputDebugString(strSQL + "\r\n");
}
CATCH_ALL(e)
{
DumpError(e, __FILE__, __LINE__);
m_stateCurrent.m_eTable = tableSave;
return NULL;
}
END_CATCH_ALL

WriteResponseDebug(strSQL);

strSQL.Empty();
strField.Empty();
strListFields.Empty();
strOrderBy.Empty();
}

<signature>
It's good to live,
Josef Wainz
Software Developer

ActiveX

Anthony988717-Dec-04 8:05

Anthony9887

17-Dec-04 8:05

Is is possible to convert an existing application(MFC) into an activex control so that it can be embedded into internet explorer. If so how can i can go about it?

Thanks

Re: ActiveX

Renjith Ramachandran17-Dec-04 22:14

Renjith Ramachandran

17-Dec-04 22:14

create an activex project and implement every function in the exe in to that ocx ,

Ninety-eight percent of the thrill comes from knowing that the thing you designed works, and works almost the way you expected it would. If that happens, part of you is in that machine.

Truecolor icon in Win NT4

Cyrus Dang17-Dec-04 6:55

Cyrus Dang

17-Dec-04 6:55

Dear all,
I used a truecolor icon for my application. Unfortunately, Win NT does not support truecolor icon. How can I change the icon to a 256-color one (in run-time) when it runs in Win NT4?
Best regards,

Re: Truecolor icon in Win NT4

Anders Molin17-Dec-04 16:02

Anders Molin

17-Dec-04 16:02

An ico file can contain several icons, just add a 256 color icon (using the resource editor in VS) and NT will show it automatically...

- Anders

Bill's Bar

My Photos

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