Autotester / debugger for g ++?

I just finished a project for my cryptography class and it all seems to be going well (mostly). Since the key is randomly generated, I would like to make sure that it will work for all keys. Anyway, I ran it a few times and segfault in about 30 run. I have not been able to reproduce this segfault in gdb. Does gdb have a command or is there some other method to keep the program running and then break on segfaults so I can check the stack?