Hi horde, > I used C in multi platforms many years and never encountered this unspecified It is not unspecified behavior. It is specified as undefined behavior. > I hope GCC can be consistent with the others. Maybe that's a better way. I do not think that is a better way. I think it is better to not rely on the behavior of a particular compiler for language undefined behavior. It would be nice if the compiler could ALWAYS warn about code that has undefined behavior. In some situations compilers do (or can) warn, but it is not possible to detect all situations where the code has undefined behavior for some languages (such as C). Alas. Sincerely, --Eljay