Question

我正在尝试在C＃程序中使用C语言编写的dll。我已经定义了一个包含整数和数组的简单结构。数组的长度不一定相同。我还编写了一个简单的代码，以便更好地理解它为什么不起作用。

C＃程序初始化此结构并用数据填充此数组，然后传递给dll。为了检查这是否正常，dll将此结构的数组内容复制到另一个数组（已在C＃中初始化）。最后，C＃程序打印两个应该相同的数组，而不是大小写。

执行没有显示错误，但似乎dll无法正确解释结构的内容。我试图使用一些元帅指令，但我对它们并不熟悉，所以它没有帮助。以下是代码，C和C＃，非常感谢您的帮助。

托马斯

    #THE C# CODE

    #region DeclareStruct
    [StructLayout(LayoutKind.Sequential)]
    public struct Test
    {
        public double[] theVector;
        public int nElements;    
    }
    #endregion DeclareStruct

    #region DLLFunctions
    [DllImport("TestLib.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "readStruct")]
    public static extern void readStruct(ref Test theStruct, double[] a);
    #endregion DLLFunctions


    static void Main(string[] args)
    {

        //delcare struc
        Test myStruct = new Test();
        myStruct.nElements = 10;//will not be always 10
        myStruct.theVector = new double[myStruct.nElements];

        //fills myStruct.theVector
        for (int i = 0; i < myStruct.nElements; i++) myStruct.theVector[i] = i * i;

        //delcare the array a which should have the same content as  myStruct.theVector
        double[] a = new double[myStruct.nElements];

        // Initialize unmanged memory to hold the struct.
        //IntPtr pnt = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(myStruct)));
        //Marshal.StructureToPtr(myStruct, pnt, false);

        //executes dll
        readStruct(ref myStruct, a);

        //display myStruct.theVector and a
        Console.WriteLine("This is theVector");
        for (int i = 0; i < myStruct.nElements; i++) Console.WriteLine(myStruct.theVector[i].ToString());

        Console.WriteLine("This is a");
        for (int i = 0; i < myStruct.nElements; i++) Console.WriteLine(a[i].ToString());


    }

            #THE C CODE

    typedef struct Test
    {
        double* theVector;
        int nElements;
    }
    Test;


    __declspec (dllexport) void readStruct(Test *myTest, double *a)
    {       
        int i;
        for (i = 0; i < myTest->nElements; i++) a[i] = myTest->theVector[i];
    }

将包含预定义数组的struct从C＃传递给C

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