C / C++ / MFC

26-Sep-04 16:47

Hi,

I have written a program in which I have included another file in which my whole class declaration is defined. It is compiling without any errors but givin linking errors. I did reffered to Microsofts reference over net for tht error.. but didn't get anything from it...here is my code...

Main program (heel.cpp)...
#include <fstream.h>
#include <iostream.h>
#include <math.h>
#include <conio.h>
#define phi 3.1412
#include "geom.cpp"

void main()
{.......
....
Cube *C = new Cube[50];
....
for(...)
C[i].set_values(dis,dim,res1);
...
..
}

Another program (geom.cpp) in which the class is defined, where all the methods are defined in this file only....(here i haven't included any header files)
class Cube
{
public:
--data members declaration.....

public:
Cube();
void set_values(double x, double y, int z);
void set();
void process();
int check(int i, int j);
};

this is the error tht i am getting...

Linking...
heel.obj : error LNK2001: unresolved external symbol "public: static int (* Cube::bound1)[2]" (?bound1@Cube@@2PAY01HA)
Debug/heel.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

any help is appreciated....

thanks in advance,

Suman

Muhammad Azam26-Sep-04 19:06

26-Sep-04 19:06

suman if i am getting it correctly, you have a file named heel.cpp (main file) and a file named geom.cpp which contains your class declaration. if this is the case then the linker error is due to the fact that you have declared member functions in your class but havn't defined them any where
to remove the linker error either write you geom.ccp file as

class Cube
{
public:
--data members declaration.....

public:
 Cube()
 {
 }
 void set_values(double x, double y, int z)
 {
 }
 void set()
 {
 }
 void process()
 {
 }
 int check(int i, int j)
 {
 }
};

or define you members in a separet file e.g

file:geom.h

class Cube
{
public:
--data members declaration.....

public:
Cube();
void set_values(double x, double y, int z);
void set();
void process();
int check(int i, int j);
};

file: geom.cpp

#include "geom.h"

Cube::Cube()
{
}
void Cube::set_values(double x, double y, int z)
{
}
void Cube::set()
{
}
void Cube::process()
{
}
int Cube::check(int i, int j)
{
}

and in you heel.cpp file just include geom.h like this:

#include "geom.h"

Hope this will remove the linker error . plz inform me if this works or still you are getting same error

regards

Muhammad Azam
ned_azam@yahoo.com
muhammadazam_cis08@hotmail.com

Muhammad Azam26-Sep-04 19:17

26-Sep-04 19:17

also if you have an static data member in your class, like it seems that you have declared static int bound; or something like this then out side your class write int cube::bound=0; like
class cube
{
static int bound;
.
.
.
}
int cube::bound=0;

this may also be the couse of your linker error
regards

Muhammad Azam
ned_azam@yahoo.com
muhammadazam_cis08@hotmail.com

Kiran Satish27-Sep-04 10:24

27-Sep-04 10:24

Hi Azam,

thanks for ur valuable reply. Actually the second reply worked out. Its due to the static declaration in the class. Anyway now I am using direct declaration witout static.

but i want to know how to declare a static type in a class. I have tried the way u specified but then the compiler is giving me error. My bound variable is a 2D array.

once again thanks,

Suman

Muhammad Azam27-Sep-04 22:46

27-Sep-04 22:46

Hi suman
i think you are trying to declare a 2D static array of integers like this
static int bound1[10][10] in your class.

Suman, static members are basically class members and they must be defined expilicitly after your class definition. like i have declared something like static int bound1[10][10] in my geom.h file and when i compiled the program i got the same linker error as you stated, then i defined int Cube::bound1[2][2]={0}; in my geom.cpp file before defining constructor or any other member then there was no linker error ( notice class declaration in .h file and definition in .cpp file.

suman, in C++ we say static members are like 'metadata' (data about data). e.g if you want to know at some time how many objects of your class are there in memory then static member is used for this purpose like

file: test.h

class ABC
{
 public:
   static int counter;
 private:
   [some members]
 public
   ABC();
   ~ABC();
   [some methods]
};

file: test.cpp

int ABC::counter = 0;

ABC::ABC
{ 
 counter++;
}
ABC::~ABC
{
 counter--;
}

and in main progeam
file: Main.cpp

#include "test.h"
void main (void)
{
 ABC obj1,obj2,obj3;
 cout<<ABC::counter;
}

output: 3

Kiran Satish28-Sep-04 7:57

28-Sep-04 7:57

Hi Azam,
thanks for ur advice and suggestion and explaining in such a detail. I got ur point and defined in the same way tht u have explained.

cheers,
pavan.

Suman

Muhammad Azam28-Sep-04 19:14

28-Sep-04 19:14

you are welcome

its my pleasure if i could be of any help for you in this regard.

Azam

Kiran Satish28-Sep-04 19:27