问个简单的有关问题，单选框怎么有初始的值

问个简单的问题，单选框如何有初始的值？
做了两个单选框，如何才能有打开的时候怎么样才能默认选中一个呢？

------解决方案--------------------
在头文件public里手动添加
// Dialog Data
//{{AFX_DATA(CLayOut)
enum { IDD = IDD_LAYOUT };
int m_layout1; //手动添加的项
//}}AFX_DATA

在相应的.cpp里
CMyDlg::CMyDlg(CWnd* pParent /*=NULL*/)
: CDialog(CMyDlg::IDD, pParent)
{
//{{AFX_DATA_INIT(CMyDlg)
m_layout1 = 0; //默认选中第一个
//}}AFX_DATA_INIT
}
------解决方案--------------------
BOOL CButtonsDlg::OnInitDialog()
{
CDialog::OnInitDialog();
************************************************************************************

CButton* pButton = (CButton*)GetDlgItem(IDC_CREDITCARD); //IDC_CREDITCARD为单选钮
ASSERT(pButton);
if (pButton)
{
pButton-> SetCheck(BST_CHECKED);
}
************************************************************************************
return TRUE; // return TRUE unless you set the focus to a control
// EXCEPTION: OCX Property Pages should return FALSE
}
------解决方案--------------------
Sets or resets the check state of a radio button or check box.


void SetCheck(
int nCheck
);



Parameters
nCheck
Specifies the check state. This parameter can be one of the following:

Value Meaning
BST_UNCHECKED
Set the button state to unchecked.

BST_CHECKED
Set the button state to checked.

BST_INDETERMINATE
Set the button state to indeterminate. This value can be used only if the button has the BS_3STATE or BS_AUTO3STATE style.


Remarks
This member function has no effect on a pushbutton.