How can I test an Object to see if it already exists?

REF : Visual C++ 6

Hello

I have created a dialog and it's class;

I created a member variable of the created dialog class in the main dialog;

CGraphDlg m_dlgGraph;

Later in the Main dialog code I create the second dialog and show it.

void CSmithGraphDlg::OnBopenGraph()
{
// TODO: Add your control notification handler code here

m_dlgGraph.Create(IDD_SGRAPH, this);
m_dlgGraph.ShowWindow(SW_SHOW);
}

Is there a way to test 'm_dlgGraph' variable, before I try and create the dialog object to see if is already attached to an existing dialog object?

if there is a method for this, will it work with other objects ?
thanks

You can test m_hWnd to see if it's valid or not.

Also, you can declare your variable dinamically:

Code:

---

CGraphDlg *m_dlgGraph = NULL;

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and test it for NULL:

Code:

---

void CSmithGraphDlg::OnBopenGraph()
{
  // TODO: Add your control notification handler code here
  if(m_dlgGraph == NULL)
    m_dlgGraph = new CGraphDlg();
  m_dlgGraph->.Create(IDD_SGRAPH, this);
  m_dlgGraph->ShowWindow(SW_SHOW);
}

---

This way you can delete ar recreate it over an over:

Code:

---

void CSmithGraphDlg::OnBdeleteGraph()
{
  // TODO: Add your control notification handler code here
  if(m_dlgGraph != NULL)
  {
    delete m_dlgGraph;
    m_dlgGraph = NULL;
  }
}

---

You can test whether there is another CGraphDlg active in the app by putting a static member in the CGraphDlg class.
DWORD m_dwCount;
This variable is shared by all objects of the CGraphDlg class because it is static. Initialize it at the beginning of the .cpp file:
DWORD CGraphDlg::m_dwCount = 0;

In the constructor of CGraphDlg:
m_dwCount++;

In the destructor of CGraphDlg:
m_dwCount--;

You could then:
CGraphDlg dlg; //Create object
if (dlg.m_dwCount > 1)
//There is already another object of the dlg class

Steve

Quote:

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Originally posted by hickock6
Is there a way to test 'm_dlgGraph' variable, before I try and create the dialog object to see if is already attached to an existing dialog object?

---

Code:

---

if(!m_dlgGraph.GetSafeHwnd())
  m_dlgGraph.Create(IDD_SGRAPH, this);

m_dlgGraph.ShowWindow(SW_SHOW);

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Quote:

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Originally posted by hickock6
if there is a method for this, will it work with other objects ?

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It will work with all 'CWnd' derived ones... :cool:

Thanks to all the answers :

Will let you know how it works out..
Agian thanks for the help