获得从本地的dll结构数组到C#应用程序 [英] Get an array of structures from native dll to c# application
问题描述
我有一个C#.NET CF 2.0项目中,我需要在本地C ++ DLL调用方法。这种本地方法返回一个类型 TableEntry
的数组。在本地方法被调用的时候,我不知道该阵列将多大。
如何从本地DLL到C#项目拿到桌子吗?下面是有效的什么,我现在有。
//在C#.NET CF 2.0项目
[StructLayout(LayoutKind。顺序)]
公共结构TableEntry
{
[的MarshalAs(UnmanagedType.LPWStr)]公共字符串描述;
公众诠释项目;
公众诠释another_item;
公众的IntPtr some_data;
}
函数[DllImport(MYDLL.DLL,
CallingConvention = CallingConvention.Winapi,
字符集= CharSet.Auto)]
公共静态外部布尔的GetTable(参考TableEntry []表);
SomeFunction()
{
TableEntry []表= NULL;
BOOL成功=的GetTable(参见表格);
//在这一点上,该表是空的
}
//在本地C ++ DLL
的std ::矢量< TABLE_ENTRY> global_dll_table;
的externC__declspec(dllexport)的布尔的GetTable(TABLE_ENTRY *表)
{
表=&放大器; global_dll_table.front();
返回真;
}
谢谢,
PaulH
< DIV CLASS =h2_lin>解决方案
在编组未知大小的数组从原产地到管理,我觉得最好的策略如下:
- 键入托管代码数组
的IntPtr
- 有本地代码同时返回数组和大小参数。
- 手动从
的IntPtr
数据元帅在托管方自定义结构。
因此我会进行以下更改你的代码。
本机:
的externC__declspec(dllexport)的布尔的GetTable(TABLE_ENTRY **表,__int32 * pSize)
{
*表=&放大器; global_dll_table.front();
*的pSize =的static_cast&所述; INT32>(global_dll_table.size());
返回真;
}
管理
函数[DllImport(MYDLL.DLL,
CallingConvention = CallingConvention.Winapi,
字符集= CharSet.Auto)]
[返回:的MarshalAs(UnmanagedType .I1)]
公共静态外部布尔的GetTable(出的IntPtr arrayPtr,OUT INT大小);
公共静态列表< TableEntry>的GetTable(){
VAR arrayValue = IntPtr.Zero;
变种大小= 0;
无功名单=新名单,LT; TableEntry>();
如果(的GetTable(出arrayValue,出大小)!){
返回列表;
}
VAR tableEntrySize = Marshal.SizeOf(typeof运算(TableEntry));
为(VAR I = 0; I<大小;我++){
VAR CUR =(TableEntry)Marshal.PtrToStructure(arrayValue的typeof(TableEntry));
list.Add(现);
arrayValue =新的IntPtr(arrayValue.ToInt32()+ tableEntrySize);
}
返回列表;
}
I have a C# .NET 2.0 CF project where I need to invoke a method in a native C++ DLL. This native method returns an array of type TableEntry
. At the time the native method is called, I do not know how large the array will be.
How can I get the table from the native DLL to the C# project? Below is effectively what I have now.
// in C# .NET 2.0 CF project
[StructLayout(LayoutKind.Sequential)]
public struct TableEntry
{
[MarshalAs(UnmanagedType.LPWStr)] public string description;
public int item;
public int another_item;
public IntPtr some_data;
}
[DllImport("MyDll.dll",
CallingConvention = CallingConvention.Winapi,
CharSet = CharSet.Auto)]
public static extern bool GetTable(ref TableEntry[] table);
SomeFunction()
{
TableEntry[] table = null;
bool success = GetTable( ref table );
// at this point, the table is empty
}
// In Native C++ DLL
std::vector< TABLE_ENTRY > global_dll_table;
extern "C" __declspec(dllexport) bool GetTable( TABLE_ENTRY* table )
{
table = &global_dll_table.front();
return true;
}
Thanks, PaulH
When marshalling an array of unknown size from native to managed I find the best strategy is as follows
- Type the array to
IntPtr
in managed code - Have the native code return both the array and a size parameter.
- Manually marshal the data from
IntPtr
to the custom struct on the managed side.
As such I would make the following changes to your code.
Native:
extern "C" __declspec(dllexport) bool GetTable( TABLE_ENTRY** table, __int32* pSize )
{
*table = &global_dll_table.front();
*pSize = static_cast<int32>(global_dll_table.size());
return true;
}
Managed:
[DllImport("MyDll.dll",
CallingConvention = CallingConvention.Winapi,
CharSet = CharSet.Auto)]
[return: MarshalAs(UnmanagedType.I1)]
public static extern bool GetTable(out IntPtr arrayPtr, out int size);
public static List<TableEntry> GetTable() {
var arrayValue = IntPtr.Zero;
var size = 0;
var list = new List<TableEntry>();
if ( !GetTable(out arrayValue, out size)) {
return list;
}
var tableEntrySize = Marshal.SizeOf(typeof(TableEntry));
for ( var i = 0; i < size; i++) {
var cur = (TableEntry)Marshal.PtrToStructure(arrayValue, typeof(TableEntry));
list.Add(cur);
arrayValue = new IntPtr(arrayValue.ToInt32() + tableEntrySize);
}
return list;
}
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