I am giving you the source of a little program I made. It's a bank simulation. The problem is that when I turn zerolink off in XCode, I get a bunch of errors about multiple declarations. The problem is that I have not declared anything more than once, and I have also put #ifndef in all headers! Can you please take a look at it? And also, can you tell me why the program gives many more errors in GCC 3? I thought I had done everything right.