Thanks very much Brian, my code now works. I had to remove quite a lot of programmes that I was linking in and recompile them all using gcc 3.3. Now everything has been made with gcc 3.3 and all works. Thanks for the info on the shared libraries, I didn't know that, you've saved me a lot of time. I guess you only learn about things like this when they don't work and you have to fix them. What's really confused me is the fact that I was definitely using gcc 3.4 on my old (deleted) RHEL4 that was linking everything together. It was also compiling my code much faster as well. A quick ldd on a backup executable shows that I did in fact get both libstdc++.so.5 & so.6 linked in together and working, and I didn't even know it! Thanks once again John On Fri, 2007-04-27 at 07:54 -0700, Brian Dessent wrote: > John Morris wrote: > > > My programme compiles and links fine using a RHEL3 PC, gcc 3.4 with > > libstdc++.so.5. It runs reasonably well and I am happy. > > Are you sure that's not 3.2 or 3.3 that your old RH system was using? > According to <http://gcc.gnu.org/onlinedocs/libstdc++/abi.html>, the > last version that used v5 was gcc v3.3.3. > > > I have just changed my laptop (different from PC above) from RHEL3 to > > ubuntu as everything about it looks and feels nicer. However, ubuntu > > ships with libstdc++.so.5 and libstdc++.so.6, both in /usr/lib. I have > > got gcc 3.4. > > > > My code compiles under ubuntu, but it is linking the libstdc++.so.6 into > > everything instead of libstdc++.so.5. This causes me great problems and > > my programme dies almost straight away. I use 3rd party open-source > > software which relies on libstdc++.so.5 and I will need to run it on the > > RHEL3 machine mentioned before, that only has libstdc++.so.5. > > > > Does anybody know what flag I need to set in my Makefile to get > > everything linked with libstdc++.so.5? I can't have any trace of libstdc > > ++.so.6, 'ldd me.exe | grep libstdc++.so.6' has to come up blank. > > You can't just pick and choose which version of the library is used. It > is highly coupled to the version of gcc; in other words, the version of > gcc that you use will determine which version of libstdc++ your code > gets linked to, and nothing else. They go hand in hand. > > Generally when you are aiming for binary compatibility across multiple > systems/platforms, the only way to achieve this is to set the compile > environment to the oldest combination of libraries and compilers that > you want to support. There is no way to go backwards, i.e. use a recent > gcc but link to an older library. If you want to produce binaries that > still link against an older libstdc++ you'll have to install gcc 3.3 on > your system and use that. The libstdc++.so.5 that ubuntu provides is > for compatibility for existing binaries that were compiled with gcc 3.3, > it is not possible to link against it for new programs compiled with gcc > 3.4 or 4.x. > > Brian
