将结构从非托管C ++传递到C# [英] Passing struct from unmanaged C++ to C#
问题描述
注意:最后的工作解决方案是编辑之后!
Note: The final working solution is after the edit!
我希望有人能帮助我解决一个问题以解决最近几天。
I hope someone can help me with a problem I've been trying to solve for the last few days.
我试图将结构从非托管C ++ DLL传递到C#脚本。这是我到目前为止:
I am trying to pass a struct from a unmanaged C++ DLL to a C# script. This is what I have so far:
C ++
EXPORT_API uchar *detectMarkers(...) {
struct markerStruct {
int id;
} MarkerInfo;
uchar *bytePtr = (uchar*) &MarkerInfo;
...
MarkerInfo.id = 3;
return bytePtr;
}
C#
[DllImport ("UnmanagedDll")]
public static extern byte[] detectMarkers(...);
...
[StructLayout(LayoutKind.Explicit, Size = 16, Pack = 1)]
public struct markerStruct
{
[MarshalAs(UnmanagedType.U4)]
[FieldOffset(0)]
public int Id;
}
...
markerStruct ByteArrayToNewStuff(byte[] bytes){
GCHandle handle = GCHandle.Alloc(bytes, GCHandleType.Pinned);
markerStruct stuff = (markerStruct)Marshal.PtrToStructure(
handle.AddrOfPinnedObject(), typeof(markerStruct));
handle.Free();
return stuff;
}
...
print(ByteArrayToNewStuff (detectMarkers(d, W, H, d.Length) ).Id);
问题是这样工作,但打印的值完全关闭有时候最大的int值)。
The problem is that this works, but the value printed is completely off (sometimes it prints around 400, sometimes max int value).
我猜想有一些问题,我如何编组C#中的结构。任何想法?
I'm guessing that there's something wrong with how I marshalled the struct in C#. Any ideas?
编辑:
C ++
struct markerStruct {
int id;
};
...
EXPORT_API void detectMarkers( ... , markerStruct *MarkerInfo) {
MarkerInfo->id = 3;
return;
}
C#
[DllImport ("ArucoUnity")]
public static extern void detectMarkers( ... ,
[MarshalAs(UnmanagedType.Struct)] ref MarkerStruct markerStruct);
...
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
public struct MarkerStruct
{
public int Id;
}
...
detectMarkers (d, W, H, d.Length, ref markerInfo);
print( markerInfo.Id );
推荐答案
您返回一个指向局部变量的指针已经被销毁之前.NET可以读取它。这是一个坏主意在纯C ++和一个坏主意与p / invoke。
You're returning a pointer to a local variable which has already been destroyed before .NET can read it. That's a bad idea in pure C++ and a bad idea with p/invoke.
而是,有C#传递一个结构的指针(只是使用 ref
关键字)和C ++代码只是填充它。
Instead, have C# pass a pointer to a structure (just use the ref
keyword) and the C++ code just fill it in.
这篇关于将结构从非托管C ++传递到C#的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!