arrays - 如何将数组从 Fortran 返回到 C？

Question

我想知道使用 Fortran 中的 ISO C 绑定将数组从 Fortran 返回到 C 的正确方法是什么。

Answer 1

简单的例子：

#include <stdio.h>
#include <stdlib.h>

void F_sub ( float * array_ptr );

int main ( void ) {

   float * array_ptr;

   array_ptr = malloc (8);

   F_sub (array_ptr);

   printf ( "Values are: %f %f\n", array_ptr [0], array_ptr [1] );

   return 0;
}

和

subroutine F_sub ( array ) bind (C, name="F_sub")

   use, intrinsic :: iso_c_binding
   implicit none

   real (c_float), dimension (2), intent (out) :: array

   array = [ 2.5_c_float, 4.4_c_float ]

end subroutine F_sub

Answer 2

function return_an_array result(res) bind(c)
    use iso_c_binding

    implicit none

    interface
        function malloc(n) bind(c,name='malloc')
            use iso_c_binding
            type(c_ptr)::malloc
            integer(c_size_t),value::n
        end function malloc
    end interface

    type,bind(c)::c_array_2d
        type(c_ptr)::p
        integer(c_int)::dims(2)
    end type

    type(c_array_2d)::res
    integer(c_size_t)::res_len

    real(c_double),pointer::a(:,:)

    res_len = 3*2*c_double
    res%p = malloc(res_len)
    res%dims = [3, 2]

    call c_f_pointer(res%p, a, [2,3])

    a(1,1) = 1.0
    a(2,1) = 2.0
    a(1,2) = 3.0
    a(2,2) = 4.0
    a(1,3) = 5.0
    a(2,3) = 6.0

end function