将2d数组从Fortran传递到C [英] Passing 2d array from Fortran to C

问题描述

我很难将2D数组从Fortran传递到C函数.但是，毕竟支持，下面的代码可以100％起作用.

I am having difficulty passing a 2d array from Fortran to C function. However, after all the support the following code is functional 100%.

以下是我的C函数:

#include <stdio.h>
  void print2(void *p, int n)
  {
     printf("Array from C is \n");
     double *dptr;
     dptr = (double *)p;
     for (int i = 0; i < n; i++)
     {
        for (int j = 0; j<n; j++)
            printf("%.6g \t",dptr[i*n+j]);

        printf("\n");
     }
  }

以下是我的Fortran代码:

The following is my Fortran code:

        program linkFwithC
        use iso_c_binding
        implicit none 
        interface
          subroutine my_routine(p,r) bind(c,name='print2')
            import :: c_ptr
            import :: c_int
            type(c_ptr), value :: p
            integer(c_int), value :: r
          end subroutine
        end interface


        integer,parameter ::n=3
        real (c_double), allocatable, target :: xyz(:,:)
        real (c_double), target :: abc(3,3)
        type(c_ptr) :: cptr
        allocate(xyz(n,n))
        cptr = c_loc(xyz(1,1))

        !Inputing array valyes

        xyz(1,1)= 1
        xyz(1,2)= 2
        xyz(1,3)= 3
        xyz(2,1)= 4
        xyz(2,2)= 5
        xyz(2,3)= 6
        xyz(3,1)= 7
        xyz(3,2)= 8
        xyz(3,3)= 9


        call my_routine(cptr,n)
        deallocate(xyz)
      pause
      end program linkFwithC

代码运行良好；但是，C中的数组元素需要重新组织.

The code runs fine;however, the array elements in C need to be re-organized.

注意，要在Visual Studio环境中将C函数与FORTRAN代码链接，应遵循以下步骤:

Note, In order to link the C function with the FORTRAN code in a visual studio environment, one should follow the following step:

• 在静态库项目中编写C函数
• 构建.lib文件
• 创建FORTRAN项目并编写代码
• 将.lib文件添加到FORTRAN项目中(只需将其添加到源文件中)
• 编译并运行.

谢谢， 阿纳斯(Anas)

Thanks, Anas

推荐答案

像传递的数组有两种存储方式-ROW-MAJOR和COLUMN-MAJOR. C使用行优先，fortran使用列优先.

There are two ways arrays like you are passing are stored - ROW-MAJOR and COLUMN-MAJOR. C uses row-major, fortran uses column-major.

您将必须按照在Fortran中创建的顺序访问C中的数组元素.

You will have to access the array elements in C in the order as it was created in fortran.

与其发布代码块，不如在编写代码之前更好地理解它.为了清楚起见，请参见以下内容: http://en.wikipedia.org/wiki/Row-major_order

Rather than post a code block, you might do better to understand it before you code it. See this for clarity: http://en.wikipedia.org/wiki/Row-major_order

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