Hi, Dave, Thanks a lot for your help. Best Regards Jian-ping -----"Dave Korn" <dave.korn@xxxxxxxxxx> wrote: ----- To: <Jian-ping.Hui@xxxxxxxxxx>, <gcc@xxxxxxxxxxx> From: "Dave Korn" <dave.korn@xxxxxxxxxx> Date: 01/17/2006 07:04PM cc: <gcc-help@xxxxxxxxxxx> Subject: RE: Forward declaration issue on gcc 3.4.3(New) Jian-ping.Hui wrote: > Now my question is: Why there are such difference between the two version > gcc? This is a VFAQ. See http://gcc.gnu.org/gcc-3.4/changes.html#cplusplus > Could I compile b.cpp by simply changing some compiler options? No, you will have to fix the invalid code to be fully compliant with the C++ language standard. cheers, DaveK -- Can't think of a witty .sigline today....