[Boost-users] How to cast form string to number safely?

Dear boost-users: I am really sorry for asking shch a silly question, but I really need your help! boost::lexical_cast is a great function to do casting. If I want is to cast from string to a "long long" type value, I can use the follow: long long llVar = lexical_cast<long long>("123456789"); It is alright in this circs, but what if: lexical_cast<long long>("9999999999999999999999999999999999999999999999999999999999999999999999999999"); This is an obvious overflow, but I have no way to handle this error, it returns a wrong number without throwing an exception! Any suggestion? Thank you very much!!! Kevin