Shared Vector Variables Among Multiple C++ files

Question

I want to share(globalize) some vector variables(V1 and V2) between two cpp files(A.cpp and B.cpp). I have already defined both V1 and V2 in A.h by the following commands.

extern vector<uint64_t> V1;
extern vector<uint64_t> V2;

I also have added #include "A.h" to both A.cpp and B.CPP files. Can anyone let me know what else should I do to be able to access the elements of V1 and V2 in both of these CPP files?

Thanks in Advance

Answer 1

First, you need to pick up place where your vectors should be defined. Let's say that you choose A.cpp.

In A.cpp (only in one file - defining same object in multiple files will yield multiple defined symbols error) define vectors as global variables:

 vector<uint64_t> V1;
 vector<uint64_t> V2;

In B.cpp (and in all other files from which you want to access V1 and V2) declare vectors as extern. This will tell linker to search elsewhere for the actual objects:

 extern vector<uint64_t> V1;
 extern vector<uint64_t> V2;

Now, in the linking step V1 and V2 from B.cpp will be connected to the V1 and V2 from A.cpp (or whereever these objects are defined).