Hi john.

11-May-04 11:28:20, john dumas wrote to All


 jd> {at}MSGID: 1:261/38 7beeefa8
 jd> {at}TZUTC: -0500
 jd> {at}CHARSET: LATIN-1
 jd> From: john dumas 

 jd> Lets say I have an array of  char * pointers in  dll.hpp called array1. I
 jd> can
 jd> include dll.hpp in both the dll.cpp and prog.cpp. And the program will be
 jd> satified when I try to use it

 jd>   ( array1 in dll.hpp )
 jd>              / \
 jd>             /    \
 jd>      dll.cpp   prog .cpp

 jd> int __stdcall (*foo)( char **array1 );

 jd> foo = ...GetProcAddress...

 jd> But, what if  array1 is in dll.cpp

 jd>   ( array1 in dll.cpp )
 jd>              |
 jd>              |
 jd>         prog .cpp

 jd> int __stdcall (* foo)( char **array1 );

 jd> Undefined symbol   ... array1

This is generic advice....

put an extern definition of array1 in in the header file

extern char *array1[ HOW_BIG ];

defining HOW_BIG the aray is isn't critical in case prog1 does sizeof(arrray1)
putting the definition in the header file means that if you declare it
incorrectly in the library source file the compiler should spot the
difference and let you know.

if you leave the extern out you'll end up with two arrays one belonging to
the library and one to the program... which may not be what you want...

I don't know if this advice is compatible with microsoft windows...
I've heard that non private variables local to DLLs get shared between all
programs that link that DLL... AFAIK that feature is unique to windows.

 -=> Bye <=-

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