Hi

I'm tring to learn how to write a program with multiple files.
I have a working program composed by a file main.c with many functions inside. I've tried to put one function outside.
I mean that now i have:

1) main.c ( with the #include " function1.h" and where i call the function1),
2) funtion1.c ( with the #include " function1.h", and where I write what the function1 do),
3)function1.h (where all i do is just to declare the function1)

but now the program doesn't not compile and i get the linker error:

Code:
/main.c:32: undefined reference to `function1'
collect2: ld returned 1 exit status
Anyone can help?

Thanks

D.