SendMessage( (HWND) hWnd, // handle to destination window BM_GETCHECK, // message to send (WPARAM) wParam, // not used; must be zero (LPARAM) lParam // not used; must be zero );Return Values can be one of the following. BST_CHECKED:Button is checked. BST_INDETERMINATE:Button is grayed, indicating an indeterminate state (applies only if the button has the BS_3STATE or BS_AUTO3STATE style). BST_UNCHECKED:Button is cleared
(HWND) hWnd, // handle to destination window
BM_GETCHECK, // message to send
(WPARAM) wParam, // not used; must be zero
(LPARAM) lParam // not used; must be zero
);Return Values can be one of the following. BST_CHECKED:Button is checked.
BST_INDETERMINATE:Button is grayed, indicating an indeterminate state (applies only if the button has the BS_3STATE or BS_AUTO3STATE style).
BST_UNCHECKED:Button is cleared