[maemo-developers] Undefined reference error

[From: Dave Neary]

Hi,

Pallavi Kandhare wrote:
> I have 2 files : list1.h and list1.c, and I call some functions defined
> in list1.h in main function of main.c.

First, some definitions:

Functions are generally declared in headers, and defined in C files.

A declaration of any function is required before you can use it.

> list1.h is included in both list1.c and main.c.

So your function is declared in main.c, and should compile OK.

> Still i am getting the following error :
> /test1file/src/main.c undefined reference to function-name

This is a linker error - it means that at the time you are creating the
executable, the definition of the function is not being found.

> The list1.o file is not created. What changes do i need to make to my
> Makefile in order to remove this error.

That all depends on what your Makefile looks like now, doesn't it? ;)


Generally it should resemble this:

all: list1.o main.o
	cc -o my_prog list1.o main.o

list1.o:
	cc -c list1.c

main.o:
	cc -c main.c

(there are ways to make this shorter, using pattern rules).

Cheers,
Dave.

-- 
maemo.org docsmaster
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