如何將 C++ struct 數組編組為 C#

Question

我計划將一個 c++ 結構數組編組到 c# 中，我嘗試了很多方法來做到這一點，但函數返回的數組始終是一個空數組。 我不知道是什么問題。 這是我的 C++ 代碼：

# include<iostream>
typedef  struct
{
    float x, y, z;
}cfloat3;

extern "C" __declspec(dllexport)  cfloat3* Test();
extern "C" __declspec(dllexport)  void freeMemory(cfloat3 * a);

cfloat3* Test()
{
    cfloat3* a = new cfloat3[5];
    for (int i = 0; i < 5; i++)
    {
        a[i].x = 1;
        a[i].y = 1;
        a[i].z = 1;
    }
    return a;
}
void freeMemory(cfloat3* a)
{
    delete[] a;
}

這是我的 C# 代碼

namespace ConsoleApp3
{
    [StructLayout(LayoutKind.Sequential)]
    struct cfloat3
    {
        public float x, y, z;
    }
    class Program
    {
        [DllImport("Dll1.dll", EntryPoint = "Test")]
        public static extern IntPtr Test();

        [DllImport("Dll1.dll", EntryPoint = "freeMemory")]
        public static extern void freeMemory( IntPtr a);
        static void Main(string[] args)
        {

            int length = 5;
            int size = Marshal.SizeOf(typeof(cfloat3)) * length;

            IntPtr pBuff = Marshal.AllocHGlobal(size);
            cfloat3[] pClass = new cfloat3[length];
            pBuff=Test();

            IntPtr[] bb = new IntPtr[length];
            Marshal.Copy(pBuff, bb, 0, length);

            for (int i = 0; i < length; i++)
            {
                pClass[i] = (cfloat3)Marshal.PtrToStructure(bb[i],typeof(cfloat3));

                Console.WriteLine(pClass[i].x);
                Console.WriteLine(pClass[i].y);
                Console.WriteLine(pClass[i].z);

            }
            Marshal.FreeHGlobal(pBuff);
            Console.ReadKey();
        }
    }
}

運行這個程序，我得到“System.AccessViolationException: Attempted to read or write protected memory。這通常表明其他內存已損壞。”

Answer 1

您需要在每個字段中使用帶有SizeConst MarshalAs注釋， SizeConst C# 的返回類型分別映射到 C++ 結構和返回類型

請參考這個答案Marshaling C++ struct to C#