Re: Button error

From:

David Wilkinson <no-reply@effisols.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 24 May 2006 22:09:03 -0400

Message-ID:

<ugQzsA6fGHA.324@TK2MSFTNGP02.phx.gbl>

liuerbin2000@163.com wrote:

// GASDoc.h : interface of the CGASDoc class
CGASDoc : public CDocument
{
public:
    int m_dmaxA;
.......
}

// A.h : header file
#include"GASDoc.h"
class CA: public CDialog
{
public:
    CGASDoc* pDoc;
    void someaction();
    int m_dmaxA;
}

// B.h : header file
class CB : public CDialog
{
// Dialog Data
    //{{AFX_DATA(CB)
    enum { IDD = IDD_B };
    int m_dmaxA;
    //}}AFX_DATA

//A.cpp
void CA::someaction()
{

    CB dlg;
    if(dlg.DoModal()==IDOK)
    {
          pDoc->m_dmaxA=m_dmaxA=dlg.m_dmaxA;
             }

}

its all right when compiling , but , when runing it has a wrong .
Usingthe debug tool , i find it stop at the location :
       pDoc->m_dmaxA=m_dmaxA=dlg.m_dmaxA;
it said that :
Unhandled exception in GAS. exe :0xC0000005 ; Access Violation

liuerbin:

Where is CA::pDoc initialized? Nowhere, I think.

Try to communicate from the outside to the inside, not the other way around.

void CMyDoc::OnSomeAction()
{
   CDialog1 dlg;
   dlg.m_var = m_var;
   if(dlg.DoModal() == IDOK)
   {
      m_var = dlg.m_var;
   }
   UpdateAllVies(NULL);
}

void CDialog1::OnSomeAction()
{
   CDialog2 dlg;
   dlg.m_var = m_var;
   if(dlg.DoModal() == IDOK)
   {
      m_var = dlg.m_var;
   }
}

See how each "parent" knows about the "child", but not vice versa. No
"reaching out".

David Wilkinson