c# - 如何将包含 void* 的结构从 c++ 传递到 c#？

Question

我有一个问题，我在网上找不到答案。我想从我的 c# 代码中调用一个 c++ 函数。c++ 函数声明为：

int read(InfoStruct *pInfo, int size, BOOL flag)

具有以下结构

typedef struct
{
    int ID; 
    char Name[20];
    double value;
    void *Pointer;
    int time;
}InfoStruct;

在我的 C# 代码中，我写道：

 public unsafe struct InfoStruct
 {
    public Int32 ID;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 20)]
    public string Name;
    public Double value;
    public void *Pointer;
    public Int32 time;
  };

[DllImport("mydll.dll", SetLastError = true, CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
        public static extern unsafe int read(out MeasurementInfoStruct[] pInfo, int size, bool flag);

我试图运行代码，但它崩溃了，所以我想我在结构上犯了一个错误，特别是 void* 但我不知道该放什么。也可能是函数返回一个结构数组，也许我没有正确调用它。你能帮我解决这个问题吗？多谢。

Answer 1

我创建了一个测试应用程序，代码如下，它工作正常......

// CPP code

typedef struct
{
    int ID; 
    char Name[20];
    double value;
    void *Pointer;
    int time;
}InfoStruct;

int WINAPI ModifyListOfControls(InfoStruct *pInfo, int size, bool flag)
{

    int temp = 10;
    pInfo->ID = 10;
    strcpy(pInfo->Name,"Hi");
    pInfo->value = 20.23;
    pInfo->Pointer = (void *)&temp;
    pInfo->time = 50;
    return 0;
}
/***************************************************/
// This is C# code
[StructLayout(LayoutKind.Sequential)]
public struct InfoStruct
{
    public Int32 ID;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 20)]
    public string Name;
    public Double value;
    public IntPtr Pointer;
    public Int32 time;
};


[DllImport(@"D:\Test\Projects\Release_Build\WeldDll.dll", CallingConvention = CallingConvention.Winapi)]
public static extern int ModifyListOfControls(ref InfoStruct pInfo, int size, bool flag);// ref InfoStruct pi);

public static void Main()
{
    InfoStruct temp = new InfoStruct();

    temp.Pointer = new IntPtr();

    ModifyListOfControls(ref temp, 200, true);

    Console.WriteLine(temp.ID);
    Console.WriteLine(temp.Name);
    Console.WriteLine(temp.time);
    Console.WriteLine(temp.value);


    Console.ReadLine();
}

/ * ** * **输出* ** * ** * * 10 Hi 50 20.23 * ** * ** * ** * ** * ** * ** * * /