从C到c#的封送结构

本文关键字：结构 | 更新日期: 2023-09-27 18:09:33

编辑:我过于简化了我的例子…在实际代码中，我在没有正确使用wcscpy_s的情况下将值分配给strMyStringx，所以我只是传递指针，而不是分配值，当值被封送到托管代码中时，指针超出了范围…

我正试图从C到c#编组一个具有三个字符串属性的结构体，但我无法在c#中获得结构体的定义。所有属性打印为垃圾。是我的编组错误还是我的属性类型错误?

我的自定义结构:

typedef struct _MY_STRUCT_STRING {
    LPWSTR strMyString1;
    LPWSTR strMyString2;
    LPWSTR strMyString3;
}MY_STRUCT_STRING, *PMY_STRUCT_STRING;

我的C函数返回指向这个结构体的指针数组:

bool bEnumerateString(OUT LONG &i_arr_size, OUT PMY_STRUCT_STRING* &pArrStringStruct)
{
// [...] function simplified to demonstrate building a pointer to an array of struct*
long i_arr_size = 3
PMY_STRUCT_STRING *ptr_arr_string = (PMY_STRUCT_STRING *)malloc(sizeof(PMY_STRUCT_STRING)* i_arr_size);
for (int i = 0; i < i_arr_size; i++) {
    ptr_arr_string[i] = (PMY_STRUCT_STRING)malloc(sizeof(MY_STRUCT_STRING));
    ptr_arr_string[i]->strMyString1 = L"String 1"; // This would work. In the real code I was assigning values from another array and mistakenly passed the pointer rather than doing wcscpy_s
    ptr_arr_string[i]->strMyString2 = L"String 2";
    ptr_arr_string[i]->strMyString3 = L"String 3";
}
pArrStringStruct = ptr_arr_string;
return true;
}
c#: 

    //Import the DLL with my function
    [DllImport("My.dll", SetLastError = true, CharSet = CharSet.Unicode, EntryPoint = "bEnumerateString")]
    internal static extern bool bEnumerateString(out long count, out IntPtr pArrStringStruct);
     // Define the C# equivalent of the C struct
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    internal struct MY_STRUCT_STRING
    {
        [MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 8)]
        public string strMyString1;
        [MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 8)]
        public string strMyString1;
        [MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 8)]
        public string strMyString1;
    }
   [...]
    // Code to marshal (try... catch etc removed for succinctness)
   IntPtr pArrStruct = IntPtr.Zero;
   long lCount = 0;
   bool bResult = false;
   bResult = bEnumerateString(out lCount, out pArrStruct);
   if (!bResult)
   {
    // Marshal to deref pointer
       IntPtr[] pArrStructList = new IntPtr[lCount];
       for (ulong i = 0; i < (ulong)lCount; i++)
       {
            pArrStructList[i] = Marshal.ReadIntPtr(pArrStruct, Marshal.SizeOf(typeof(IntPtr)) * (int)i);
       }

    // Marshal pointers to struct
       var lstMyStringStrct = new List<MY_STRUCT_STRING>(pArrStructList.Length);
       foreach (IntPtr ptr in pArrStructList)
       {         
            lstMyStringStrct.Add((MY_STRUCT_STRING)Marshal.PtrToStructure(ptr, typeof(MY_STRUCT_STRING)));
       }
    // Enumerate struct
       foreach (MY_STRUCT_STRING myStr in lstMyStringStrct)
       {
           // All of these outputs are garbage
           Console.WriteLine("strMyString1: " + myStr.strMyString1);
           Console.WriteLine("strMyString2: " + myStr.strMyString2);
           Console.WriteLine("strMyString3: " + myStr.strMyString3);
        }
    }

从C到c#的封送结构

我看到一个问题。你的c++结构使用LPWSTR(指针)，而你的c#代码期望固定大小的字符数组。

从

更改字符串
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 8)]
public string strMyString1;

，当c++结构定义为

时使用:
char strMyString1[8];

: 

[MarshalAsAttribute(UnmanagedType.LPWStr)]
public string strMyString1;
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