Question

我正在从C＃程序调用Fortran DLL。我设法传递一个Fortran派生类型作为参数，但是当调用一个返回派生类型作为返回值的函数时，我得到一个NullPointerException。

我怀疑我在C＃端DLLImport中做错了什么。

Fortran图书馆：

module FortranCallBack
USE ISO_C_BINDING
IMPLICIT NONE

TYPE, BIND(C) :: FOO
   INTEGER :: A, B
END TYPE

CONTAINS

SUBROUTINE Test(myFoo) BIND(C)
   !DEC$ ATTRIBUTES DLLEXPORT :: Test

   TYPE(FOO), INTENT(IN) :: myFoo
   write (*,*) "Foo: ", myFoo%A, " ", myFoo%B
END SUBROUTINE

FUNCTION FuncTest() BIND(C) RESULT(RES)
   !DEC$ ATTRIBUTES DLLEXPORT :: FuncTest
   TYPE(FOO) :: RES
   RES = FOO(42, 13)
END FUNCTION

和C＃代码调用它：

using System.Runtime.InteropServices;

namespace ConsoleApplication1
{

    [StructLayout(LayoutKind.Sequential)]
    public class FOO 
    { 
        public int a; 
        public int b; 
    }


    class Program {

        static void Main(string[] args)
        {
            var f = new FOO { a = 1, b = 2 };
            // This works
            Test(f);

            // Here I get NullPointerException...
            FOO myFoo = FuncTest();
        }

        [DllImport("fortran_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl, EntryPoint = "test")]
        public static extern void Test( [In] FOO foo );

        [DllImport("fortran_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl, EntryPoint = "functest")]
        public static extern FOO FuncTest();
    }
}

代码使用英特尔Fortran 10.1和.NET framework 4.0进行编译

NullPointerExcception当C＃调用Fortran函数返回派生类型时

0 个答案: