Swift import C framework

add.h

int f1(int);
int f2(int);

add1.c

#include <stdio.h>

int f1(int x) {
    printf( "f1: %d;", x );
    return x+1;
}

add2.c

#include <stdio.h>

int f2(int x) {
    printf( "f2: %d;", x );
    return x+2;
}

useadd.c

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

int main(int argc, char** argv){
    printf("  main %d\n", f1(1));
    printf("  main %d\n", f2(10));
    return 0;
}