! gcc -c csub.c
! F csub.o f_calls_c.f95
! ./a.out
! The value of i is 42
! The value of d is 4.200000
! The value of a[3] is 3.300000
! The value of c is abc

program f_calls_c
   integer, parameter :: n = 42
   integer, parameter :: double = selected_real_kind(9)
   real(kind=double), pointer :: dp
   integer :: i
   real, dimension(0:9) :: ra = ( (/ (1.1*i, i=0,9) /) )
   character(len=3) :: s = "abc"

   allocate (dp)
   dp = 4.2_double
   call csub (s)
end program f_calls_c

! file csub.c:

! void csub_ (int *i, double *d, float a[], char *c) {
!
! printf("The value of i is %d\n", *i);
! printf("The value of d is %f\n", *d);
! printf("The value of a[3] is %f\n", a[3]);
! printf("The value of c is %s\n", c);
! 
! }