[混编] C调用Fortran dll

Program void
  use ISO_C_BINDING
  implicit none
  interface
    subroutine print_a(s,a) bind(C,name='print_a_')
      import
      type(C_FUNPTR) , value :: s
      type(C_PTR) , value :: a
    end subroutine print_a
    subroutine ss(a) Bind( c , Name = "ss_" )
    implicit none
    integer a
   end subroutine ss
  end interface
  integer , target :: a = 256
  call print_a( c_funloc(ss) , c_loc(a) )
  print * , a
end program void
!************************************
    !  需要传递的子程序如下：
!************************************
   subroutine ss(a) Bind( c , Name = "ss_" )
    implicit none
    integer a
    a = a + 1
    print *,'a=',a
   end subroutine ss

#include <stdio.h>
extern void ss_(int a);  //我自己写的传递进来的ss子程序
void print_a_(void* t, int a){
  //  int b=(int)t;
  ss_(a);  //调用传递进来的子程序
  //  printf("ct_=%p\n",t);
  printf("ca=%d\n", a);
}