How to access to variable on parent class mfc - c++

Question

I have a Dialog on MFC application.
MyDialog :
{
int variable1;
int variable2;
Class1 cls = new Class1();
}
And in class1()
Class1()
{
void Function1()
void Function2()
}
--
So How to Access and return to variable1 in Class1::Function1()
Class1::Function1()
{
MyDialog dlg = new MyDialog ();
Get x = dlg->variable1; //if like this, variable1 alway=0, because in above line, i'm define new myDialog()
}
I think to delegate on .NET but in MFC application, I can't get it done ?

Answer 1

You can
"extend" your constructor, by adding a pointer to the parent in your child dialog and access your variable or call public functions (requires header of parent)
use SendMessage and handle the messages in your parent dialog
use GetParent in-place and dynamic_cast it to your parent dialog (requires header of parent)
1.
Class1::Class1(MyParent *parent)
{
m_parentPointer = parent;
}
void Class1::Function1(void)
{
m_parentPointer->myPublicVariable;
}
2.
void Class1::Function1(void)
{
CWnd *parent = GetParent();
if (parent)
parent->SendMessage(WM_YOUR_MESSAGE, yourWPARAM, yourLPARAM);
}
//MessageMap of parent
ON_MESSAGE(WM_YOUR_MESSAGE, ParentClassHandler)
LRESULT Parent::ParentClassHandler(WPARAM wp, LPARAM lp)
{
//Process
}
3.
void Class1::Function1(void)
{
CWnd *parent = GetParent();
if (parent)
{
Parent *p = dynamic_cast<Parent*>(parent);
if (p)
{
//Process
}
}
}

Answer 2

If Class1::Function1() needs to access the dialog, then you need a pointer to the dialog in Function1.
void Class1::Function1(MyDialog *dlg) {
}
If you want to store the dialog pointer permanently, then adjust the constructor of Class1.
class Class1 {
public:
Class1(class MyDialog *dlg_) : dlg(dlg_) {}
class MyDialog *dlg;
}
Another, probably better, way to implement it, is to move the code that needs to access Class1 and MyDialog into global functions or into MyDialog member functions. But which way to go depends on what the classes do and which design you want.

Answer 3

You have to start with basic C++ classes before diving in to this. But here is how it's done:
MyDialog dlg = new MyDialog ();
dlg->variable1 = 1; //set the variable
if (IDOK == dlg->DoModal()) //wait for user to click OK
{
int x = dlg->variable1; //get the variable
}
However, dlg->variable1 is not changed unless you drive your own class and do something to change it.
For example, you can use Dialog Data Exchange to assign variable1 to a check box.
void MyDialog::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
DDX_Check(pDX, IDC_CHECK1, variable1);
}
To try it, use Visual Studio's dialog wizard to create a check box and an edit box. It will probably create check box with resource id IDC_CHECK1, an edit box with resource id set to IDC_EDIT1.
Another option:
use OnInitDialog to assign variable to dialog controls
use OnOK() to get variables from dialog controls:
:
BOOL MyDialog::OnInitDialog()
{
//put `CString m_string1;` in class declaration
BOOL result = CDialog::OnInitDialog();
SetDlgItemText(IDC_EDIT1, m_string1);
return result;
}
void MyDialog::OnOK()
{
GetDlgItemText(IDC_EDIT1, m_string1);
CDialog::OnOK();
}