How can I update edit control in dialog after hit send?

Question

I have a dialog with 2 edit control, one is for user-input, another one is readable only for display whatever user input and send button. I'm trying to display user-input when they hit send button by setting a variable for edit_control1 called m_message. But it seems doesn't work. I have a minimal experience on C++ so not sure how to solve this properly.

this is my .cpp file:

// dlg_AskAI.cpp : implementation file
//

#include "StdAfx.h"
#include "afxdialogex.h"
#include "resource.h"
#include "dlg_AskAI.h"


// dlg_AskAI dialog

IMPLEMENT_DYNAMIC(dlg_AskAI, CDialog)

dlg_AskAI::dlg_AskAI(CWnd* pParent /*=nullptr*/)
    : CDialog(IDD_ASKAI, pParent)
    , m_message(_T(""))
{

}
CString m_message;
dlg_AskAI::~dlg_AskAI()
{
}

void dlg_AskAI::DoDataExchange(CDataExchange* pDX)
{
    CDialog::DoDataExchange(pDX);
    DDX_Text(pDX, IDC_EDIT3, m_message);
}


BEGIN_MESSAGE_MAP(dlg_AskAI, CDialog)
    ON_BN_CLICKED(IDC_BUTTON2, &dlg_AskAI::OnBnClickedButton2)
    ON_EN_CHANGE(IDC_EDIT3, &dlg_AskAI::OnEnChangeEdit3)
    ON_BN_CLICKED(IDC_SEND_BUTTON, &dlg_AskAI::OnBnClickedButton3)
    ON_BN_CLICKED(IDC_EDIT4, &dlg_AskAI::OnEnChangeEdit4)
    ON_WM_CLOSE()
END_MESSAGE_MAP()


void dlg_AskAI::OnCancel()
{
    DestroyWindow();
}
void dlg_AskAI::PostNcDestroy()
{
    delete this;
}
//Contact Us
void dlg_AskAI::OnBnClickedButton2()
{
    // TODO: Add your control notification handler code here
}


void dlg_AskAI::OnEnChangeEdit3()
{
    // TODO:  If this is a RICHEDIT control, the control will not
    // send this notification unless you override the CDialog::OnInitDialog()
    // function and call CRichEditCtrl().SetEventMask()
    // with the ENM_CHANGE flag ORed into the mask.

    // TODO:  Add your control notification handler code here

}

//Send Button
void dlg_AskAI::OnBnClickedButton3()
{
    UpdateData(true);
    CString formattedMessage;
    formattedMessage.Format(_T("Me: %s"), m_message);

    // Update the display edit control with the formatted message
    SetDlgItemText(IDC_EDIT4, formattedMessage);
    GetDlgItem(IDC_EDIT4)->UpdateWindow();
    
}


void dlg_AskAI::OnEnChangeEdit4()
{
  
}

this is my .h file :

// dlg_AskAI dialog

class dlg_AskAI : public CDialog
{
    DECLARE_DYNAMIC(dlg_AskAI)

public:
    dlg_AskAI(CWnd* pParent = NULL);   // standard constructor
    virtual ~dlg_AskAI();

// Dialog Data
#ifdef AFX_DESIGN_TIME
    enum { IDD = IDD_ASKAI };
#endif

protected:
    virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support

    DECLARE_MESSAGE_MAP();
public:
    afx_msg void OnBnClickedButton2();
    afx_msg void OnEnChangeEdit3();
    afx_msg void OnBnClickedButton3();
    afx_msg void OnEnChangeEdit4();
    afx_msg void OnCancel();
    virtual void PostNcDestroy();
private:
    CString m_message;
};

Answer 1

In your CPP file you are declaring a second CString:

CString m_message;

See?

dlg_AskAI::dlg_AskAI(CWnd* pParent /*=nullptr*/)
    : CDialog(IDD_ASKAI, pParent)
    , m_message(_T(""))
{

}
--> CString m_message; <--
dlg_AskAI::~dlg_AskAI()
{
}

That should not be there as you have one in the header file.