I am submitting a source of my BankAccount program. My problem is that when I try to load a file generated by this program, I end up with a message like this: Code: ZeroLink: unknown symbol '__ZN9CustomStr16containsVariableEv' bankaccount2 has exited due to signal 6 (SIGABRT). Actually, this program is a revision of the old one which needed a polish (the one in the link is one-year old, when I started learning programming). But the strange thing is that the old one works just fine. PS. Yes, I know that I could do the file input by not using classes, but I wanted to do that just because I intend to use those libraries for other programs, too. Can anybody have a look at it?