Some Fortran/C linking test

aux.f90

FUNCTION f1(a,b,c)
	USE, INTRINSIC :: ISO_C_BINDING
	INTEGER :: a, b, c
	INTEGER :: f1

	REAL, PARAMETER :: f2=3, f4=5

	f1 = a*b*c

	WRITE (*,*) 'fort func=a*b*c=', f1

END FUNCTION f1

SUBROUTINE simple(i)
	USE, INTRINSIC :: ISO_C_BINDING
	REAL, INTENT(IN)  :: i
	INTEGER :: a,b,c,d

	WRITE(*,*) 'simple i=', i

	a = 2
	b = 3
	c = 3

	!d = f1(a,b,c)
!	WRITE (*,*) 'fort called func=',d
	
END SUBROUTINE simple


SUBROUTINE vect(V, Q)
	USE, INTRINSIC :: ISO_C_BINDING
	!REAL, INTENT(IN)  :: V(3)
	REAL  :: V(3)
	REAL  :: Q(3)

	WRITE(*,*) 'fortvec V(1)=', V(1)
	WRITE(*,*) 'fortvec V(2)=', V(2)
	WRITE(*,*) 'fortvec V(3)=', V(3)

	WRITE(*,*) 'fortvec Q(1)=', Q(1)
	WRITE(*,*) 'fortvec Q(2)=', Q(2)
	WRITE(*,*) 'fortvec Q(3)=', Q(3)

	V(3) = 5.
END SUBROUTINE vect

main.c

#include <stdio.h>

int main() {
	printf("This is cpp\n");

	float i=5;
	simple_(&i);

	float V[3];
	V[0] = 2.3; V[1] = 5.3; V[2] = 3.2;

//	float Q[3] = {1,2,3};
	float Q[3];
	Q[0] = 2.3; Q[1] = 5.3; Q[2] = 3.2;

	vect_(V, Q, 3, 3);

	printf("V[2] = %f\n", V[2]);

	int a=2, b=3, c=1;
	int res = 0;

	res = f1_(&a,&b,&c);

	//printf("res func(%f,%f,%f) = %f\n", a,b,c,res);
	printf("res func(%i,%i,%i) = %i\n", a,b,c,res);

}

Makefile

CC=gcc
F90=gfortran

all:
	${CC} -Wall -c main.c
	${F90} -c aux.f90
	${CC} -o test main.o aux.o -lgfortran

clean:
	rm *.o test

Done in June 23, 2016.