(.text+0x7): undefined reference to

[hassuna003]

hi
i am a new programer in c
i have write a simple app and i have a problem withe combiling
my program include one header file and 2 c

fun.h

#include<stdio.h>
void f();
/******EOF*******/
fun.c

#include"fun.h"
void f(){
printf("HI\n");
}
/*****EOF********/
and tha main is

#include"fun.h"
int main(int argc,char* argv[]){
f();
}
/*****EOF********/

and when i trying to compile the program i receive this message
/tmp/ccwzuzqh.o: In function `main':
main.c.text+0x7): undefined reference to `f'
collect2: ld returned 1 exit status

is there any one can help me ?

[mstabie]

It is not the compiler that is complaining, it is the linker, the thing that prepares the object files into a executable. Try
cc main.c fun,c
I suspect you did
cc main.c

[user-f11]

Maybe the C compiler assumes f() as an internal C routine and calls a modified version of the name. Rewrite the code by defining f() as an external function and test it with the gcc (GNU compiler collection).

[guus.leeuw.jr]

Hello,

fun.h should declare
extern void f(void);

to be fully compliant with ANSI C.

The keyword extern indicates that this now is a declaration. Across all compilation units in your program, there can thus only be one definition, but this f.h can now be included everywhere without actually defining the function f().

Regards,
Guus

[Rubberman]

You need to declare and define f() as "void f(void)", and then you need to make sure you link fun.o with main.o when you compile and link them to make your executable.

[user-f11]

IMHO Guru Lewis Junior is right: in order to become a great programmer (some day) you should always read at first 'Das Original' (in this case the ISO Standard of C++, ANSI).

http://www.open-std.org/jtc1/sc22/wg...2010/n3092.pdf
There is a new version of it (with insignificant amendments).

However, if you compare this standard with the Handbook of C++ (that is adorned with the Pirate Logo) you will see a lot of differences.


To start with something, read first the standards of the developers.

[occam25]

hi hassuna,
I found this (dont remember where) about the structure you should follow in your C projects. Hope it helps

C PROGRAM STRUCTURE

// module.h

#ifndef _MODULE_H // To avoid multiple inclusion
#define _MODULE_H

#include “another_include.h” // other includes, if necesary.

#define DEFINITION // Defines

typedef long int INT32; // typedefs

extern int global_variable;
extern void global_function(int x);

#endif

// module.c

#include <include1.h> // as many includes as we need
#include “include2.h”

#include “module.h” // each .c has to incluye its .h

int global_variable = 1234; // global variable defined as
// extern in the .h

static char local_variable; // local Variable only visible
// from module.c

void global_function (int x){ // global_function implementation
. . .
}

static int local_function(char c){ // funcion_local Implementation
. . .
}