具有多个翻译单元的LNK2005错误

Question

I'm writing a small arbitrary-precision arithmetic library, and I have encountered a problem:

I have exception class, derived from std::exception , in my exception.h and exception.cpp . Exception.h is included by vector.h , and vector.h , in turn, is included by my_long.h.

So the problem is: when I'm including my_long.h in main.cpp and my_long.cpp, I'm getting a redefinition linker error LNK2005 for all functions in my exception class, which is quite logical, because I'm including this class in two different translation units and then trying to link them together.

Is there any possible workarounds, or what am I doing wrong?

Answer 1

You have two choices. You can either mark all of the functions in my_long.h as inline, which allows multiple identical definitions, or you can move the function definitions to my_long.cpp and put forward declarations for them in my_long.h.

Typically, to keep the header file readable, you should do the second except for very small functions.