发信消息

void CControlDlg::OnBnClickedButtonSend(){    // TODO: 在此添加控件通知处理程序代码    CString strWindowTitle =  _T("ClientDemo");      CString strDataToSend = _T("成功通信");      HWND hOtherWnd = ::FindWindow(NULL,_T("DLL窗口")); //_T("YK Application"),NULL    if (hOtherWnd != NULL && ::IsWindow(hOtherWnd))      {          COPYDATASTRUCT cpd;          cpd.dwData = 0;          cpd.cbData = strDataToSend.GetLength() * sizeof(TCHAR);          cpd.lpData = (void*)strDataToSend.GetBuffer(0);          HRESULT hResult = ::SendMessage(hOtherWnd, WM_COPYDATA, (WPARAM)(AfxGetApp()->m_pMainWnd), (LPARAM)&cpd);          strDataToSend.ReleaseBuffer();      }  }

DLL接收端先添加WM_COPYDATA中添加消息映射

BEGIN_MESSAGE_MAP(CWGDLG, CDialogEx)    ON_WM_COPYDATA()//消息映射    ON_BN_CLICKED(IDC_BUTTON1, &CWGDLG::OnBnClickedButton1)    ON_BN_CLICKED(IDOK, &CWGDLG::OnBnClickedOk)END_MESSAGE_MAP()

然后回函数中写代码

BOOL CWGDLG::OnCopyData(CWnd* pWnd, COPYDATASTRUCT* pCopyDataStruct){    // TODO: 在此添加消息处理程序代码和/或调用默认值    //AfxMessageBox((LPCSTR)(pCopyDataStruct->lpData));    //MessageBox(NULL, _T("成功通信"), MB_OK);      if (pCopyDataStruct != NULL)      {          LPCTSTR pszText = (LPCTSTR)(pCopyDataStruct->lpData);          DWORD dwLength = (DWORD)(pCopyDataStruct->cbData);          TCHAR szRecvText[1024] = {
   0};          memcpy(szRecvText, pszText, dwLength);          MessageBox(szRecvText, _T("成功通信"), MB_OK);      }      return CDialogEx::OnCopyData(pWnd, pCopyDataStruct);}