calling MFC edit control GetWindowText member can't compile - c++

Question

My code:
//the auto generated stuff (by right-click on editbox add variable to control option)
CEdit edit_name;
void CSendMessageWithActualDataDlg::DoDataExchange(CDataExchange* pDX)
{
CDialogEx::DoDataExchange(pDX);
DDX_Control(pDX, IDC_EDIT_NAME, edit_name);
}
Looks OK so far, right?
void dofoo()
{
//IDE shows error squiggle at dot "name.GetWi" with no pop-up
//details given except the object's blurb text
CString foostring= edit_name.GetWindowTextW();
//error C2661: 'CWnd::GetWindowTextW': no overloaded function takes 0 arguments
// or instead with no parentheses added:
// no IDE error indication
CString foostring= edit_name.GetWindowTextW;
//error C3867: 'CWnd::GetWindowTextW': non-standard syntax; use '&' to create a pointer to member
}
According to:
Read text from edit control in MFC and VS2010
You can then retrieve the text in the edit box like this:
CEdit m_EditCtrl;
// ....
CString filePath1 = m_EditCtrl.GetWindowText()
.
.
.
// Yes, now it works...
I swear, this is like pulling teeth.

Answer 1

Apparently, this is all about convenience. Since you already know how to call CWnd::GetWindowText, but find it too cumbersome to use, just wrap everything up in a free function:
CString GetWindowText(CWnd const& wnd) {
CString s;
wnd.GetWindowText(s);
return s;
}
You can call that, passing in any object that (publicly) derives from CWnd (such as the CEdit edit_name) and get a CString object you can use any which way. (C++17 introduced guaranteed copy elision, meaning that s will never need to get copied.)
If you need to pass it into other Windows API functions that expect an LPCTSTR, CString implements operator PCXSTR that implicitly converts things as needed, e.g.
AfxMessageBox(GetWindowText(edit_name));

Answer 2

When you add a EDIT control to a dialog, and you go to map it to a variable, you have two choices:
Control
Value
If you select Value, then you can map it to a CString:
This creates the DDX_Text entry that was referred to in the comments:
void CTestDialogDlg::DoDataExchange(CDataExchange* pDX)
{
CDialogEx::DoDataExchange(pDX);
DDX_Text(pDX, IDC_EDIT1, m_strText);
}
Or, you can use GetDlgItemText if you want to just get the value directly from the control, and avoid creating a variable. This shows both:
void CTestDialogDlg::OnBnClickedButton1()
{
// This way you get the current text value from the edit control, without even creating a CEdit control member variable
CString strText;
GetDlgItemText(IDC_EDIT1, strText);
AfxMessageBox(strText);
// This way we use our mapped CString to the EDIT control
UpdateData(TRUE);
AfxMessageBox(m_strText);
}
If you do decide to map to a CEdit (a Control instead of a Value) then as you found out:
// Get the value from the control
m_editText.GetWindowText(strText);
AfxMessageBox(strText);
I assume your linked article is incorrect as GetWindowText does not return a CString.
By the way, with Visual Assist (a third-party extension) it shows the options correctly for Intellisense:
By the way, you may find this article useful (Dialog box controls and variable types). If you look at the table and find EDIT:
The above is with the previous rows on the table stripped out. As you can see, you can map the EDIT to more types of variables than just a CString.

Answer 3

this suffices:
class GetWindowText
{
CString s;
public:
GetWindowText(CWnd &w){w.GetWindowText(s);}
~GetWindowText() {}
CString operator()() {return s;}
};
just call like this:
MessageBoxW(GetWindowText(edit_name)());