question  [Linker Warning] Public symbol defined in both module

giro82 (23)   Link to this post

Hi!
I have following problem:

Namely,when I use keyword "extern" to get the value of standard variable (e.g.float,int,..) or array located in one file and use it in another file, everything works fine.
Problems appear when I recall to matrix variable (I use matrix.h library from http://www.techsoftpl.com/matrix/matlite.htm)then I got this message:

[Linker Warning] Public symbol '_slupek' defined in both module C:\PROGRAM FILES\BORLAND\CBUILDER6\PROJECTS\05.11.2009\SLUPKI.OBJ and C:\PROGRAM FILES\BORLAND\CBUILDER6\PROJECTS\05.11.2009\KATY.OBJ


Below are listings maybe someone will find mistake.

slupki.h:

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#ifndef SLUPKIH 
#define SLUPKIH 

#include "matrix.h" 


#ifndef _NO_NAMESPACE 
using namespace std; 
using namespace math; 
#define STD std 
#else 
#define STD 
#endif 

#ifndef _NO_TEMPLATE 
typedef matrix<double> Matrix; 
#else 
typedef matrix Matrix; 
#endif 
///////////////////////////////// 
Matrix slupki(); 

#endif //SLUPKIH

slupki.cpp:

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#include "matrix.h" 
#include "slupki.h" 
////////////////////////////// 
Matrix slupek(6,2); //matrix variable declaration
double x_1[6]; 
double x_2[6]; 

Matrix slupki() 
{ 
        for(int i=0;i<6;i++) 
        { 
         slupek(i,0)=3; 
         slupek(i,1)=3; 
         x_1[i]=slupek(i,0); 
         x_2[i]=slupek(i,1); 
        } 
        return(slupek); 
}

katy.h:

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#ifndef KATYH 
#define KATYH 

#include "matrix.h" 

#ifndef _NO_NAMESPACE 
using namespace std; 
using namespace math; 
#define STD std 
#else 
#define STD 
#endif 

#ifndef _NO_TEMPLATE 
typedef matrix<double> Matrix; 
#else 
typedef matrix Matrix; 
#endif 
////////////////////////////// 
Matrix katy(); 

#endif //KATYH

katy.cpp:

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#include "slupki.h" 
#include "matrix.h" 
///////////////////////////////////// 
double y_1[6]; 
double y_2[6]; 
//extern double x_1[6]; 
//extern double x_2[6]; 
Matrix kat(6,2); 
extern Matrix slupek(6,2); 

Matrix katy() 
{ 
       for(int i=0;i<6;i++) 
       { 
        kat(i,0)=slupek(i,0)+1; // recall to 1.column of matrix slupek(6,2) 
        kat(i,1)=slupek(i,1)+1; // recall to 2.column of matrix slupek(6,2) 
        y_1[i]=kat(i,0); 
        y_2[i]=kat(i,1); 
       } 
        return(kat); 
}

ftest.cpp:

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//--------------------------------------------------------------------------- 

#include <vcl.h> 
#pragma hdrstop 

#include "ftest.h" 
#include "katy.h" 
#include "slupki.h" 
//--------------------------------------------------------------------------- 
#pragma package(smart_init) 
#pragma resource "*.dfm" 
TForm1 *Form1; 
//--------------------------------------------------------------------------- 
__fastcall TForm1::TForm1(TComponent* Owner) 
        : TForm(Owner) 
{ 
} 
//--------------------------------------------------------------------------- 

void __fastcall TForm1::Button2Click(TObject *Sender) 
{ 
Close();        
} 
//--------------------------------------------------------------------------- 

void __fastcall TForm1::Button1Click(TObject *Sender) 
{ 
slupki(); 
katy(); 
extern double x_1[6]; 
extern double x_2[6]; 
extern double y_1[6]; 
extern double y_2[6]; 

for(int i=0;i<6;i++) 
{ 
StringGrid1->Cells[0][i]=AnsiString(x_1[i]); 
StringGrid1->Cells[1][i]=AnsiString(x_2[i]); 
StringGrid2->Cells[0][i]=AnsiString(y_1[i]); 
StringGrid2->Cells[1][i]=AnsiString(y_2[i]); 
} 
} 
//---------------------------------------------------------------------------


When I put extern double x_1[6] and extern double x_2[6] above katy() function in katy.cpp additionally I slash out extern Matrix slupek(6,2) and replace respectively slupek(i,0) and slupek(i,1) with x_1[i] and x_2[i] my program works fine.


Maybe the problem is in matrix.h library.

I work with Builder 6 Enterprise.
Any ifnormation concerning matrix.h can be found under http://www.techsoftpl.com/matrix/matlite.htm

I will be appreciate for any remarks.
guestgulkan (1306)   Link to this post
katy.cpp

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#include "slupki.h" // ?????? Is this right or should it be #include "katy.h"
#include "matrix.h"
jsmith (3807)   Link to this post
This can't be right, but I don't know why it compiles without error:

  
extern Matrix slupek(6,2);


It should be

  
extern matrix slupek;

giro82 (23)   Link to this post
It should be #include "katy.h" but the outcome is the same as for #include "slupki.h"
guestgulkan (1306)   Link to this post
But then ftest.cpp: includes both these files like this:


ftest.cpp:
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#include "katy.h" 
#include "slupki.h"


so you are no further forward.
You need to re-arrange your global variables
giro82 (23)   Link to this post
jsmith,

it doesn't work with:

extern matrix slupek;

I got messages like this:
[C++ Error] katy.cpp(9): E2102 Cannot use template 'matrix<T>' without specifying specialization parameters
[C++ Error] katy.cpp(9): E2040 Declaration terminated incorrectly
[C++ Error] katy.cpp(15): E2268 Call to undefined function 'slupek'
giro82 (23)   Link to this post
guestgulkan,
how to rearrange this?
guestgulkan (1306)   Link to this post
Hang on, I got a bit confused there didn't I? :-)

I got confused with slupki (which is a function) and slupek (which is a variable).
So ignore what I said in the previous posts.
//---------------------------------------------------------------

So the problem is with the declaration of the slupek variable.
This Matrix slupek(6,2); and this extern Matrix slupek(6,2); are both the same
in that they are both definitions
One should be Matrix slupek(6,2); and the other should be extern Matrix slupek;.
So pretty much as JSmith said.
Last edited on
giro82 (23)   Link to this post
Now it works, ;-)

Thanks a lot guys!

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