Visual C++ and MFC Programming 2nd Edition

Visual C++ and MFC Fundamentals Chapter 20: List-Based Controls

The nIDButton argument is the identifier of the check box whose state you want to

modify. The nCheck argument is the value to apply. It can have one of the following

values:

State Value Description

BST_UN CHECKED The check mark will be completely removed

BST_ CHECKED The button will be checked

BST_INDETERMINATE A dimmed checked mark will appear in the control’s

square. If the Tri-State property is not set or the

BS_3STATE style is not applied to the control, this value

will be ignored

Here is an example that automatically sets a check box to a dimmed appearance when the

dialog box comes up:

BOOL CCheckBoxes::OnInitDialog()

{

CDialog::OnInitDialog();

// TODO: Add extra initialization here

CheckDlgButton(IDC_CHECK_PHYSICAL, BST_INDETERMINATE);

return TRUE; // return TRUE unless you set the focus to a control

// EXCEPTION: OCX Property Pages should return FALSE

}

Alternatively, to change the state of a check box, you can call the CButton::SetCheck()

and pass of the above state values. For a check box, to set a dimmed check mark, here is

an example:

BOOL CCheckBoxes::OnInitDialog()

{

CDialog::OnInitDialog();

// TODO: Add extra initialization here

CButton *ChkPhysical = new CButton;

ChkPhysical = reinterpret_cast<CButton *>(GetDlgItem(IDC_CHECK_PHYSICAL));

ChkPhysical->SetCheck(BST_INDETERMINATE);

return TRUE; // return TRUE unless you set the focus to a control

// EXCEPTION: OCX Property Pages should return FALSE

}

To get the current state of a check box, you can call the CWnd::IsDlgButtonChecked()

method. If a check mark appears in the square box, this method will return 1. If the

square box is empty, this method returns 0. If the check box control has the BS_3STATE

style, the method can return 2 to indicate that the check mark that appears in the square

box is dimmed.