根据ID获取CEdit的句柄实例

MyApp.h和MyApp.cpp

#ifndef MY_APP_H_
#define MY_APP_H_

#include <afxwin.h>

class CMyApp:public CWinApp
{
public:
    virtual BOOL InitInstance();
};

#endif

=====================================

#include "stdafx.h"
#include "MyApp.h"

#include "resource.h"
#include "MyCustomCDialog.h"

BOOL CMyApp::InitInstance()
{
    /*
    CDialog dialog;
    dialog.Create(IDD_DIALOG_FIRST,NULL);
    dialog.ShowWindow(m_nCmdShow);
    */

    CMyCustomCDialog myDialog;
    myDialog.DoModal();
    //myDialog.ShowWindow(m_nCmdShow);

    /*myDialog.UpdateData(true);

    std::string result(myDialog.m_cstrEditFirst.GetBuffer());
    myDialog.m_cstrEditFirst.ReleaseBuffer();
    */
    ::MessageBox(NULL,"Message","Title",MB_OK);
    myDialog.DestroyWindow();

    return true;
}

CMyApp myApp;

CMyCustomCDialog.h和 CMyCustomCDialog.cpp

#ifndef MY_CUSTOM_CDIALOG_H_
#define MY_CUSTOM_CDIALOG_H_

#include <afxwin.h>
#include "resource.h"
#include <string>

class CMyCustomCDialog:public CDialog
{
public:
    CMyCustomCDialog(CWnd* pParent=NULL);

    enum{ IDD=IDD_DIALOG_FIRST };

    //Overrides
protected:
    virtual void DoDataExchange(CDataExchange* pDX);

    //Implement
protected:
    afx_msg void OnDoAction();

    DECLARE_MESSAGE_MAP()

public:
    CString m_cstrEditFirst;
};

#endif

======================================

#include "stdafx.h"
#include "MyCustomCDialog.h"

CMyCustomCDialog::CMyCustomCDialog(CWnd* pParent)
    :CDialog(CMyCustomCDialog::IDD,pParent)
{

}

void CMyCustomCDialog::DoDataExchange(CDataExchange* pDX)
{
    CDialog::DoDataExchange(pDX);
    ::MessageBox(NULL,"Message_DoDataExchange","Title",MB_OK);

    DDX_Text(pDX,IDC_EDIT_FIRST,m_cstrEditFirst);
}

BEGIN_MESSAGE_MAP(CMyCustomCDialog,CDialog)
    ON_BN_CLICKED(IDC_BUTTON_ACTION,OnDoAction)
END_MESSAGE_MAP()

void CMyCustomCDialog::OnDoAction()
{
    HWND hWnd=::GetDlgItem(this->m_hWnd,IDC_EDIT_FIRST);
    char* pChar=new char[];
    memset(pChar,'\0',);
    ::GetWindowText(hWnd,pChar,);
    m_cstrEditFirst.Format("%s",pChar);
}

Resource很简单：

sample edit box(CEdit)

　　Action(CButton)

关键代码是：

void CMyCustomCDialog::OnDoAction()
{
　　HWND hWnd=::GetDlgItem(this->m_hWnd,IDC_EDIT_FIRST);
　　char* pChar=new char[100];
　　memset(pChar,'\0',100);
　　::GetWindowText(hWnd,pChar,99);
　　m_cstrEditFirst.Format("%s",pChar);
}