Use the IUnicode::script function to determine the script of a character. Scripts are identified by the IUnicode::EScript enumeration. For example, this code shows how to determine whether a character at a specified offset in a text object is from the Roman script:
UniChar c = someText.at(0); if IUnicode::script(c) = IUnicode::kRoman { // Character is of the Roman script... }