Very easy is to find out which button is pressed:

int id;
id=GetCheckedRadioButton(ID_BFirst,ID_BLast);

id will be the ID number of the checked radio button. You must ensure that the first button ID_BFirst starts a group.

possible trouble
Buttons must be created in the right order, otherwise you have to manage by yourself number of ID in the resource file (be carefull!!!)

hope this will help

Yves Le Sant
Metrology and Measurement Unit
Fundamental and Experimental Aerodynamics Departement
ONERA Meudon
(Office National d'Etudes et de Recherches Aérospatiales)
FRANCE