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Multiple c files linking problem

jaydeep gajjar

Hi everyone !

I have basic knowledge of c programming. I want to write a multiple c file project due to many functions in my program.
so, i started to learn how to write learn multiple file program in c.

here is the example of three files which i compiled and tested on Dev-cpp compiler.it gives me the output 3.
(I used Dev-cpp to learn how to write multiple c files).

main.c file :


#include <stdio.h>
#include "other.h"

int main (void)
{
    printf("%d\n", getfavoritenumber());
    return 0;
}

other.h


#ifndef _OTHER_H_
#define _OTHER_H_

extern int getfavoritenumber(void);

#endif

other.c


#include "other.h"

int getfavoritenumber(void)
{
    return 3;
}

Now i same code i tested in keil. this gives following :

Build target 'Target 1'
compiling main.c...
linking...
*** WARNING L1: UNRESOLVED EXTERNAL SYMBOL SYMBOL: GETFAVORITENUMBER MODULE: main.obj (MAIN)
*** WARNING L2: REFERENCE MADE TO UNRESOLVED EXTERNAL SYMBOL: GETFAVORITENUMBER MODULE: main.obj (MAIN) ADDRESS: 0010H
Program Size: data=11.0 xdata=0 code=23
"test" - 0 Error(s), 2 Warning(s).

I don't know what to do? Please Help...

Parents
  • 0 in reply to Andy Neil

    Thanks for your quick reply !

    i have added the other.c file so keil compiled it successfully.

    now i have made some changes to files.

    main function calls ====> get_char function (declared and defined in vvv.h & vvv.c respectively)

    get_char calls ====> getfavoritenumber function (declared and defined in other.h & other.c respectively)

    main.c

    #include <stdio.h>
#include <p89v51rx2.h>
#include "other.h"
#include "vvv.h"

void main (void)
{

    P1=new_char();
        while(1);

}

    vvv.h

    
#ifdef __VVV_H__
#define __VVV_H__

extern int new_char(void);

#endif

    vvv.c

    
#include "vvv.h"
#include "other.h"

int new_char(void)
{
return(getfavoritenumber());
}

    other.h

    
#ifndef __OTHER_H__
#define __OTHER_H__

extern int getfavoritenumber(void);

#endif

    other.c

    
#include "other.h"

int getfavoritenumber(void)
{
    return 3;
}

    this time i have added all three files to my project (i.e. main.c,other.c & vvv.c)

    now i got this warning...

    Build target 'Target 1'
    compiling main.c...
    MAIN.C(9): warning C206: 'new_char': missing function-prototype
    compiling other.c...
    compiling vvv.c...
    linking...
    Program Size: data=9.0 xdata=0 code=31
    "test" - 0 Error(s), 1 Warning(s).

    i have included both header files in my main c file.

Reply
  • 0 in reply to Andy Neil

    Thanks for your quick reply !

    i have added the other.c file so keil compiled it successfully.

    now i have made some changes to files.

    main function calls ====> get_char function (declared and defined in vvv.h & vvv.c respectively)

    get_char calls ====> getfavoritenumber function (declared and defined in other.h & other.c respectively)

    main.c

    #include <stdio.h>
#include <p89v51rx2.h>
#include "other.h"
#include "vvv.h"

void main (void)
{

    P1=new_char();
        while(1);

}

    vvv.h

    
#ifdef __VVV_H__
#define __VVV_H__

extern int new_char(void);

#endif

    vvv.c

    
#include "vvv.h"
#include "other.h"

int new_char(void)
{
return(getfavoritenumber());
}

    other.h

    
#ifndef __OTHER_H__
#define __OTHER_H__

extern int getfavoritenumber(void);

#endif

    other.c

    
#include "other.h"

int getfavoritenumber(void)
{
    return 3;
}

    this time i have added all three files to my project (i.e. main.c,other.c & vvv.c)

    now i got this warning...

    Build target 'Target 1'
    compiling main.c...
    MAIN.C(9): warning C206: 'new_char': missing function-prototype
    compiling other.c...
    compiling vvv.c...
    linking...
    Program Size: data=9.0 xdata=0 code=31
    "test" - 0 Error(s), 1 Warning(s).

    i have included both header files in my main c file.

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