为什么Edit不显示haha
UpdateData(TRUE);
CString str;
str.Format( "%s ", "haha ");
CEdit* m_edit = (CEdit*)GetDlgItem(IDC_EDIT_CAPACITY);
m_edit-> GetWindowText(str);
UpdateData(FALSE);

[解决办法]
m_edit-> GetWindowText(str); ???

[解决办法]
UpdateData(TRUE);
CString str;
str.Format( "%s ", "haha ");
CWnd* m_edit = GetDlgItem(IDC_EDIT_CAPACITY); <===用CWnd类型
m_edit-> GetWindowText(str);
UpdateData(FALSE);