c++clinker

Can we have multiple c files to define functions for one header file?

Newbie to C and C++.

I have one .h file in which some functions are declared. I'm trying to implement the functions in two separate .c files, but when compiling I got a linker error.

Is it not allowed?

Solution

  • Yes it is allowed. Here is a very simple example:

    foobar.h: declares foo and bar

    void foo(void);
void bar(void);

    foo.c: implements foo

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

void foo(void)
{
  printf("foo\n");
}

    bar.c: implements bar

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

void bar(void)
{
  printf("bar\n");
}

    main.c: uses foo and bar

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

int main(void) {
  foo();
  bar();
  return 0;
}

    Compiling, linking and running with gcc:

    $ gcc -c foo.c
$ gcc -c bar.c
$ gcc -c main.c
$ gcc -o someprog foo.o bar.o main.o
$ ./someprog
foo
bar
$

    or

    $ gcc -o someprog foo.c bar.c main.c
$ ./someprog
foo
bar
$