I'm a new guy with ATL. So forgive me to ask this question.
Problem description:
One CEdit control is added into a ATL dialog class. It's attached in the dialog initialize function.
//Define the edit control
ATLControls::CEdit m_txtInput;
//In the OnInitDialog function
m_txtInput.Attach(GetDlgItem(IDC_INPUT_LINE));
m_txtInput.SetWindowText(_T("New directory"));
//In the public memeber function of the dialog GetInput()
//I have tried three kinds of method to get the text. But all of them are throw an
//assert exception, IsWindow() failed.
//1.
GetDlgItemText(IDC_INPUT_LINE, input);
//2.
ZeroMemory(m_lptstrInput, MAX_PATH);
m_txtInput.GetLine(0, m_lptstrInput, MAX_PATH);
//3.
BSTR input;
m_txtInput.GetWindowText(input);
Here is a topic about how to get text from CEdit but it is not working.
Why the CEdit control could be set text with the function SetWindowText() but can't get the text by the function GetWindowText()? It's really confuse me. Thanks a lot if someone could explain it for me.
Answer
CEdit is not an ATL class. Where the namespace ATLControls comes from? There is a WTL class with this name and getting text from it is easy:
ATLASSERT(Edit.IsWindow()); // Make sure the control holds a handle
CString sWindowText;
Edit.GetWindowText(sWindowText);
The method GetWindowText is coming from ATL however and wraps GetWindowTextLength and GetWindowText API. The latter MSDN article also has a code snippet showing typical usage.
Since you mention that IsWindow does not work for you, the most likely problem is that your edit control wrapper class variable just does not have a handle of a real control, and hence getting text from nothing is impossible.