Conflicting specifiers in declaration c++

Question

I use a data structure bimap

typedef boost::bimap< std::string, int > hash_bimap;
typedef hash_bimap::value_type position;
hash_bimap perm;

and it works fine in main file. However, i am interested to use it in header file to make it accessible in any other .cpp file.

when I try to make it extern in my.h like

extern typedef boost::bimap< std::string, int > hash_bimap;
extern typedef hash_bimap::value_type position;
extern hash_bimap perm;

conflicting specifiers in declaration of ‘hash_bimap’ extern typedef boost::bimap< std::string, int > hash_bimap;

typedef doesn't declare anything the linker can see, so you don't need to/can't make it extern. — kfsone, May 19 '16 at 16:46
@kfsone Thanks !! How to make it accessible to other `.cpp` file — AwaitedOne, May 19 '16 at 16:49
Just include the header with the typedefs in the other `cpp` file. — Mark B, May 19 '16 at 16:50

score 3 · Accepted Answer · answered May 19 '16 at 16:52

3

(elaborating on kfsone's comment) typedefs don't need to be extern, just the actual variable:

typedef boost::bimap< std::string, int > hash_bimap;
typedef hash_bimap::value_type position;
extern hash_bimap perm;

answered May 19 '16 at 16:52

Mark B

1 Answers1