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Export/import variables in/from a afx extension dll

Posted on 2004-10-20
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Last Modified: 2013-11-20
Hello Gurus,
I would like to export some variables from an AFX-Extension-DLL (PUTILS.DLL), and import them from another DLL. The export/import of functions and classes works fine.
I try it like this :

utils.h
====
AFX_EXT_CLASS CString sField[];

utils.c
====
CString sField={ "a", "b", "c" };

The compilation and linkage of PUTILS.DLL works fine. When I compile another DLL which uses sFieled, the compilation works, just the linker says unresolved external symbol
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Question by:DennisWood
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9 Comments
 

Author Comment

by:DennisWood
ID: 12364872
Thanks for any help.
Dennis
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LVL 12

Expert Comment

by:OnegaZhang
ID: 12365174
Don't use CString, try LPCTSTR instead.
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LVL 13

Expert Comment

by:SteH
ID: 12367164
have you added putils.lib to the project for the other DLL?
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Author Comment

by:DennisWood
ID: 12367175
RE OnegaZhang :
The same happens with a single instance of size_t
RE SteH:
Yes I have, because the functions and classes exported by PUtils working fine.

It just does not work with global variables
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Expert Comment

by:SteH
ID: 12367242
What type is the other DLL using putils.dll?
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LVL 9

Accepted Solution

by:
BeyondWu earned 250 total points
ID: 12367244
Your code seems not correct, here is the problem
utils.h
====
AFX_EXT_CLASS CString sField[];       // You defined a sField[] variable in utils.h, it's actually just a pointer CString* sField, just a definition, a symbol, at that time there no any really vaiable has been created. That's why the linker will report the unresolved external symbol error.

utils.c
====
CString sField={ "a", "b", "c" };          // You redefined another variable, it's name is sField, I even don't think you can pass the compiling. anyway it's another varaible, it has nothing to do with the AFX_EXT_CLASS CString sField[]; Even if you change it like this: CString sField[]={ "a", "b", "c" };

So, you can do like this:
utils.h
AFX_EXT_CLASS CString sField[3];   // You need to definitely tell compiler the size of your array, you can initailize it as this: CString sField[] = {"a", "b", "c"}, but if you want to separate the definition and initialization, you need to do this...

utils.c
YOu need to initailize your code like this, or use the for loop. Same reason, because you separated the definition and initialization, you have to do like this.
sField[1]="a";
sField[2]="b";
sField[3]="c";

Now, everything is ready for using in your another exe file

Good Luck
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Expert Comment

by:BeyondWu
ID: 12377154
Oops, I made a mistake, it should be
sField[0]="a";
sField[1]="b";
sField[2]="c";
0
 
LVL 9

Expert Comment

by:BeyondWu
ID: 12563206
Dan & DennisWood,

I can sure I have answered this question. You can test it on your own machine, if it doesn't work please tell me.

regards,
Wu
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