从C＃调用FORTRAN DLL并将值分配给结构数组 [英] Calling FORTRAN dll from C# and assigning values to array of structures

问题描述

我可以将 C＃结构传递给 FORTRAN 就好了。我甚至可以将一个 C＃结构的数组作为 TYPE（）的数组传递给 FORTRAN 。当我试图将值返回到 C＃时，我遇到了麻烦。这里是一个例子：

Fortran dll是：

  MODULE测试
 
类型VALUEREF 
 INTEGER * 4 :: A 
 ENDTYPE VALUEREF 
 
 CONTAINS 
 
 SUBROUTINE TEST_REF（T，N ）
！DEC $ ATTRIBUTES DLLEXPORT :: TEST_REF 
！DEC $ ATTRIBUTES ALIAS：'TEST_REF':: TEST_REF 
！DEC $ ATTRIBUTES VALUE :: N 
 IMPLICIT NONE 
 INTEGER * 4 :: A，I，N 
 TYPE（VALUEREF）:: T（N）
 A = 100 
 DO I = 1，N 
 T（I） ％A = A + I 
 END DO 
 
 END SUBROUTINE 
 END MODULE 
  

和 C＃预期结果的调用函数为：

  [StructLayout（LayoutKind.Sequential）] 
 public struct ValueRef 
 {
 public int a; 
} 
 
 [DllImport（mathlib.dll）] 
 static extern void TEST_REF（ValueRef [] t，int n）; 
 
 void Main（）
 {
 ValueRef [] T = new ValueRef [4]; 
 for（int i = 0; i  {
 T [i] .a = i; 
} 
 Console.WriteLine（Initialize）; 
 for（int i = 0; i< T.Length; i ++）
 {
 Console.WriteLine（A = {0}，T [i] .a）; 
} 
 Console.WriteLine（Call Fortran）; 
 TEST_REF（T，T.Length）; 
 for（int i = 0; i< T.Length; i ++）
 {
 Console.WriteLine（A = {0}，T [i] .a）; 
} 
} 
  

结果：

 初始化
 A = 0 
 A = 1 
 A = 2 
 A = 3 
呼叫Fortran 
 A = 0 
 A = 1 
 A = 2 
 A = 3 
  

通过FORTRAN代码调试，我发现初始值从 C＃传递给 FORTRAN 正好。这些值被新的值覆盖，并且控制被传回到 C＃中，旧值仍包含在 ValueRef 实例。



为什么我可以传递并返回一个 float 或<$ c $的数组c> int 以类似的方式，就好了。我可以通过并返回带有 ref 关键字的单数结构，并且我可以通过但不是返回和 struct ？

PS 。我正在使用Compaq Visual Fortran 6.5& .NET 3.5

PS2 。我很欣赏这方面的任何意见/想法。我完成了95％的项目，现在我遇到了这个问题。这个项目的重点是尽可能地使用结构来减少传递给函数的＃参数，并保留OOP设计的某些方面。

解决方案

过去我使用指针而不是数组来完成这项工作。我认为你的结构被复制为P / Invoke调用：

  [DllImport（mathlib.dll）] 
 static extern void TEST_REF（ValueRef * t，int n）; 
  

您需要在调用方法之前固定您的数组。

  fixed（ValueRef * pointer = t）
 {
 TEST_REF（pointer，n）; 
} 
  

编辑：
基于解决方案是将外部声明为

  [DllImport（mathlib.dll）] 
 static extern void TEST_REF（[Out] ValueRef [] t，int n）; 
  

这是关于数组封装的MSDN 参考，以及它们如何默认到 [In] 。

I can pass a C# struct into FORTRAN just fine. I can even pass an array of a C# struct as an array of TYPE() in FORTRAN. Where I run into trouble is when I tried to return values back into C#. Here is an example:

The fortran dll is:

MODULE TESTING

   TYPE VALUEREF
     INTEGER*4 :: A
   ENDTYPE VALUEREF

CONTAINS

   SUBROUTINE TEST_REF(T,N)
   !DEC$ ATTRIBUTES DLLEXPORT :: TEST_REF
   !DEC$ ATTRIBUTES ALIAS:'TEST_REF' :: TEST_REF
   !DEC$ ATTRIBUTES VALUE :: N
   IMPLICIT NONE
     INTEGER*4 :: A,I,N   
     TYPE(VALUEREF) :: T(N)      
     A = 100
     DO I=1,N
        T(I)%A = A + I
     END DO

   END SUBROUTINE
END MODULE

and the C# calling function that expects results is:

[StructLayout(LayoutKind.Sequential)]
public struct ValueRef
{
    public int a;
}

[DllImport("mathlib.dll")]
static extern void TEST_REF(ValueRef[] t, int n);

void Main()
{
    ValueRef[] T = new ValueRef[4];
    for (int i = 0; i < T.Length; i++)
    {
        T[i].a = i;
    }
    Console.WriteLine("Initialize");
    for (int i = 0; i < T.Length; i++)
    {
        Console.WriteLine("  A={0}", T[i].a);
    }
    Console.WriteLine("Call Fortran");
    TEST_REF(T, T.Length);
    for (int i = 0; i < T.Length; i++)
    {
        Console.WriteLine("  A={0}", T[i].a);
    }
}

With results:

Initialize
  A=0
  A=1
  A=2
  A=3
Call Fortran
  A=0
  A=1
  A=2
  A=3

Debugging through the FORTRAN code, I see the initial values pass from C# to FORTRAN just fine. The the values get overridden with new values and control is passed back into C# where the old values are still contained within the ValueRef instances.

Why is it that I can pass and return an array of float, or int in a similar fashion, just fine. and I can pass and return singular structures with ref keyword, and I can pass but not return and array of struct?

PS. I am using Compaq Visual Fortran 6.5 & .NET 3.5
PS2. I appreciate any comments/ideas on this. I am 95% done with my project, and now I run into this issue. The whole point of this project is to use structures as much as possible to reduce the #of arguments passed to functions and retain certain aspects of OOP design.

解决方案

I have done this in the past using a pointer, not an array. I think that your structures are being copied for the P/Invoke call:

[DllImport("mathlib.dll")]
static extern void TEST_REF(ValueRef* t, int n);

You will need to pin your array before calling the method.

fixed (ValueRef* pointer = t)
{
  TEST_REF(pointer, n);
}

Edit: Based on the comments the solution is to declare the external as

[DllImport("mathlib.dll")]
static extern void TEST_REF([Out] ValueRef[] t, int n);

Here is a MSDN reference on Marshaling of arrays, and how they default to [In].

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