C / C++ / MFC

Re: How to save the filename retrieved from a dialog class using CMFCEditBrowseCtrl?

10-Jul-17 8:07

Hello! I'm trying to browse a text file using CMFCEditBrowseCtrl (it is used in CFirstDialog Class) and use this file in another Dialog Class (named CSecondDialog Class). My problem is on how to save the filename retrieved from the CMFCEditBrowseCtrl when the CFirstDialog::OnEnChangeMfceditbrowse1() goes out of scope and then pass the filename to the CSecondDialog. Here is the code:

void CFirstDialog::OnEnChangeMfceditbrowse1()
{
        CString str;
	m_browser.GetWindowText(str); //CMFCEditBrowseCtrl m_browser (variable)
}

void CSecondDialog::OnBnClickedOk()
{
CStdioFile fileSource("here I need to put the filename retrieved from the previous dialog class", CFile::modeRead);
CStdioFile fileDest;
CString strLine;
CString strFile;
int num = 1;

while (fileSource.ReadString(strLine))
{
	strFile.Format(L"over%d.txt", num++);
	fileDest.Open(strFile, CFile::modeWrite);
	fileDest.WriteString(strLine);
	fileDest.Close();
}

fileSource.Close();

}

Richard MacCutchan10-Jul-17 21:28

Richard MacCutchan

10-Jul-17 21:28

The OnEnChangeMfceditbrowse1 method should store the file name in one of its object variables (or str) should be an object variable. The calling code can then capture that variable when the dialog returns.

Re: How to save the filename retrieved from a dialog class using CMFCEditBrowseCtrl?

Jochen Arndt10-Jul-17 21:38

Re: How to save the filename retrieved from a dialog class using CMFCEditBrowseCtrl?

10-Jul-17 21:38

It depends on how your dialog classes can be accessed and if they both exist at the same time.

A possible solution:
You need to store pointers to your dialogs when they are created (usually in the parent window).

Store the file name in a member variable of CFirstDialog and provide a public function to get the name:

C++

CFirstDialog
{
public:
    // ...
    const CString& GetFileName() const { return m_strFileName; }
protected:
    // ...
    CString m_strFileName;
};

void CFirstDialog::OnEnChangeMfceditbrowse1()
{
    m_browser.GetWindowText(m_strFileName);
}

Similar for CSecondDialog but there with a set function:

C++

CSecondDialog
{
public:
    // ...
    void SetFileName(const CString& strFileName) { m_strFileName = strFileName; }
protected:
    // ...
    CString m_strFileName;
};

You can now get and set the name from the class that holds the pointers to the dialogs. If both dialogs might not exist at the same time you have to store the file name in a member variable of that class (e.g. get the name when DoModal() returns).

Finally you need access to the upper class from CSecondDialog. If the upper class is the parent window, always of the same type, and has been passed as parent, you can use casting:

void CSecondDialog::OnBnClickedOk()
{
    CParentOfDialogs *pParent = static_cast<CParentOfDialogs*>(GetParent());
    // Use pParent here to get the stored name or retrieve it from the first dialog
    CString strFileName = pParent->m_pFirstDialog->GetFileName();
}

Otherwise you have to use a member variable in your second dialog that holds a pointer to the upper class and is initalised upon dialog creation or using a set function.

There are also other solutions and variations of the above.

lolici11-Jul-17 8:33

Re: How to save the filename retrieved from a dialog class using CMFCEditBrowseCtrl?

11-Jul-17 8:33

Is m_pFirstDialog a new variable?

Jochen Arndt wrote:
If both dialogs might not exist at the same time you have to store the file name in a member variable of that class (e.g. get the name when DoModal() returns).

The two dialogs do not exist at the same time, actually CSecondDialog gets on screen after I finish with CFirstDialog which goes out of scope. Could you explain me how to get the file name after DoModal() returns? Thank you in advance!

void CInputView::OnFirstDlg()
{
	// TODO: Add your command handler code here
	CInputDoc* pDoc = GetDocument();
	CFirstDialog DialogWindow;
        //.....
        CSecondDialog *pDlg = new CSecondDialog(this);
        //...
        pDlg->DoModal();
        delete pDlg;
}

void CMyView::OnSecondDlg()
{
	// TODO: Add your command handler code here
	CMyDoc* pDoc = GetDocument();
	CSecondDialog DialogWindow;
	DialogWindow.DoModal();
	
}

Jochen Arndt11-Jul-17 9:08

Re: How to save the filename retrieved from a dialog class using CMFCEditBrowseCtrl?

11-Jul-17 9:08

Add a member variable to the first dialog (as already described) and to the parent window. Then get the file name from the dialog after calling:

void CInputView::OnFirstDlg()
{
    CFirstDialog DialogWindow;
    DialogWindow.DoModal();
    // Get file name here before DialogWindow goes out of scope
    m_strFileName = DialogWindow.GetFileName();
    // Or (when DialogWindow.m_strFileName is public): 
    //m_strFileName = DialogWindow.m_strFileName
}

If you create the second dialog from another class (not CInputView), you have to pass the name to the other class in a similar way.

Then set the file name before calling DoModal() of the second dialog:

CSecondDialog DialogWindow;
// Pass file name before calling DoModal()
DialogWindow.SetFileName(m_strFileName);
DialogWindow.DoModal();

lolici11-Jul-17 9:18

Re: How to save the filename retrieved from a dialog class using CMFCEditBrowseCtrl?

11-Jul-17 9:18

I create the second dialog from the CInputView (the same class). I wrote it wrong above. Thank you very much for your help!I'm grateful!

lolici15-Jul-17 3:53

Re: How to save the filename retrieved from a dialog class using CMFCEditBrowseCtrl?

15-Jul-17 3:53

Could you please explain me how to store pointers to the dialogs when they are created so that I can get and set the name from the class that holds the pointers to the dialogs? I'm sorry for asking again but I got a little confused with this part.

Jochen Arndt15-Jul-17 22:00

Problem in precedence of operators.

15-Jul-17 22:00

Such is only useful with modeless dialogs. Modal dialogs will block so that there is usually no need to have a pointer.

However:

// With class member CSomeDialog *m_pSomeDlg
if (NULL == m_pSomeDlg)
{
    m_pSomeDlg = new CSomeDialog(this);
}

When doing so m_pSomeDlg must be initialised with NULL in the constructor and deleted in the destructor.

parkavikkk7-Jul-17 21:25

parkavikkk

7-Jul-17 21:25

What number will z in the sample code given below?
int z, x=5, y= -10, a=4, b=2;
z=x++ - --y *b/a;
Can anyone please solve it and explain the precedence. i am not getting right answer. Cry | :((

my answer is 2.5. but it is wrong. i am struggling in it. kindly solve it and explain. Thanks in advance. Smile | :)

Richard MacCutchan7-Jul-17 22:02

Richard MacCutchan

7-Jul-17 22:02

z=x++ - --y *b/a;
x(++) - ((--y) *b / a);
5 - (-11 * 2 / 4)
5 - (-22 / 4)
5 - (-5) // integer arithmetic ignores remainder
10

See C++ Built-in Operators, Precedence and Associativity[^].

parkavikkk7-Jul-17 22:30

parkavikkk

7-Jul-17 22:30

thank you. i am clear now

Jochen Arndt7-Jul-17 22:15

7-Jul-17 22:15

See C++ Operator Precedence - cppreference.com[^].

The first step is inserting parentheses according to the predence and order:

z = (x++) - (((--y) * b) / a);

Then replace the variables with their values:

z = (5++) - (((--(-10)) * 2) / 4);

Now solve step by step but observe the special handling of the postfix operator which will return a temporary copy that contains the value before the operation (that means x will be changed but the initial value of 5 is used for the calculation). Observe also that results might get rounded wirh integer arithmetic:

z = (5) - ((-11 * 2) / 4);
z = 5 - (-22 / 4);
// The remaining steps are left to your exercise

Victor Nijegorodov8-Jul-17 11:13

Victor Nijegorodov

8-Jul-17 11:13

parkavikkk wrote:
int z, x=5, y= -10, a=4, b=2;
z=x++ - --y *b/a;
Can anyone please solve it and explain the precedence. i am not getting right answer. my answer is 2.5. but it is wrong.

Of course it is wrong! Just because the integer number cannot be 2.5, nor 2.7, nor 2.8... Cool | :cool: