[英]Marshal struct from C to C#
編輯:我簡化了我的示例...在真實的代碼中,我沒有正確地使用wcscpy_s就將值分配給strMyStringx,所以不是分配值,我只是傳遞了指針,該指針在編組值時已超出范圍進入托管代碼...
我正在嘗試將具有三個字符串屬性的結構從C編組為C#,但是我無法在C#中正確獲取該結構的定義。 所有屬性都打印為垃圾。 我編組錯誤還是我的財產類型錯誤?
我的自定義結構:
typedef struct _MY_STRUCT_STRING {
LPWSTR strMyString1;
LPWSTR strMyString2;
LPWSTR strMyString3;
}MY_STRUCT_STRING, *PMY_STRUCT_STRING;
我的C函數返回一個指向該結構的指針數組:
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);
}
}
我看到一個問題。 您的C ++結構使用LPWSTR(指針),而您的C#代碼則需要固定大小的char數組。
從以下位置更改您的字符串:
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 8)]
public string strMyString1;
在定義C ++結構時將使用以下代碼:
char strMyString1[8];
至:
[MarshalAsAttribute(UnmanagedType.LPWStr)]
public string strMyString1;
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.