  external cfunction  ! Defined in c.c

  print *, 'This is the Fortran program; I am going to call the C function now...'
  call cfunction()
  call sum(1.0,2.0,3.0)
  call factorial(3)
  print *, 'Now we are back in Fortran again'

contains

  subroutine sum(x,y,z)

  x = x+y+z

  print *, x

  end subroutine sum

  subroutine factorial(j)

  p=1
  i=1
  do i=1,j
    p=p*i
  end do

  print *, j, "! = ", p

  end subroutine factorial

  subroutine sum2(x,y)

  p = x+y

  end subroutine sum2


end