About Code Reuse?

[huangyingw]

hello,
I wonder how to reuse another *.c file's function. To have a try and demo, I have written following codes. Would you help me to have a look, and could you give me more suggestion about code reuse in c.
\\192.168.0.7\myproject\c-c++\linux\caller\caller.c

#include "../becalled/becalled.h"

int main(void)
{
	int result= myAdd(1, 2);
	printf("result=%d",result);
	return   0;
}

\\192.168.0.7\myproject\c-c++\linux\caller\makefile

#include ../becalled/makefile #this want to be realized later.
run : caller.o
	gcc -o run caller.o
caller.o : caller.c ../becalled/becalled ../becalled/becalled.h
	gcc -c caller.c ../becalled/becalled.h ../becalled/becalled
clean :
	rm run caller.o

\\192.168.0.7\myproject\c-c++\linux\becalled\makefile

becalled: becalled.o
	gcc -o becalled becalled.o
becalled.o: becalled.c becalled.h
	gcc -c becalled.c

\\192.168.0.7\myproject\c-c++\linux\becalled\becalled.c

int myAdd(int a, int b)
{
	int result=0;
	result=a+b;
	return result; 
}

int main(void)
{
	return   0;
}

\\192.168.0.7\myproject\c-c++\linux\becalled\becalled.h

int myAdd(int a, int b);

make command output at:

root@linux-programming:~/myproject/c-c++/linux/caller# make
gcc -o run caller.o
caller.o: In function `main':
caller.c:(.text+0x13): undefined reference to `myAdd'
collect2: ld returned 1 exit status
make: *** [run] Error 1

[Nemooo]

Just compile the other file, too, i.e if you have a file main.c and it's calling a function inside another file call.c:

gcc main.c test.c

If you're including a header, you still have to add the file(s) being called from the header:

main.c:

#include "header.h"

int main(void)
{
        add(2, 3);

        return 0;
}

header.h:

int add(int, int);

add.c:

int add(int a, int b)
{
        return a + b;
}

Would be compiled with:

gcc main.c add.c

You want to read up on header files and include guards.

[huangyingw]

Just compile the other file, too, i.e if you have a file main.c and it's calling a function inside another file call.c:

gcc main.c test.c

If you're including a header, you still have to add the file(s) being called from the header:

main.c:

#include "header.h"

int main(void)
{
        add(2, 3);

        return 0;
}

header.h:

int add(int, int);

add.c:

int add(int a, int b)
{
        return a + b;
}

Would be compiled with:

gcc main.c add.c

You want to read up on header files and include guards.

Thanks for your guidance. While, I really don't like to have the add re-compiled again, so I may seek to use the dll instead.