http://cpplover.blogspot.jp/2015/03/blog-post_30.html C vs Fortran

c_sum.c

__attribute__((noinline)) int c_sum(int *data, int n)
{
	int result = 0;
	for(int i = 0; i < n; ++i){
		result += data[i];
	}
	return result;
}

f_sum.f90

integer(c_int) function f_sum(arr, size) bind(c)
  use iso_c_binding
  implicit none
  type(c_ptr), value :: arr
  integer(c_int), value :: size
  integer(c_int), dimension(:), pointer :: p
  call c_f_pointer(arr, p, [size])
  f_sum = sum(p)
end

main.c

#include <stdio.h>
#include <sys/resource.h>

extern int c_sum(int *, int);
extern int f_sum(int *, int);

//#define sum c_sum
#define sum f_sum

enum { c = 2 << 20 };
volatile int result[c];

int main()
{
	struct rusage r1, r2;
	int const n = 2 << 12;
	int data[n];
	getrusage (RUSAGE_SELF, &r1);
	for(int i = 0; i < c; ++i){
		result[i] = sum(data, n);
	}
	getrusage (RUSAGE_SELF, &r2);
	long double t1 =
		r1.ru_utime.tv_sec
		+ (long double)r1.ru_utime.tv_usec / 1000000000;
	long double t2 =
		r2.ru_utime.tv_sec
		+ (long double)r2.ru_utime.tv_usec / 1000000000;
	printf("%Lf\n", t2 - t1);
	return 0;
}