如何从Windows Phone上的C＃项目调用C ++ DLL函数

该主题看起来像重复的，但不是：

主要项目是：

C# Project -> WP8.1 Silverlight
or
C# Project -> WP8.1 RT

C ++ DLL项目有3个选项：

C++ ProjectA ->Windows Runtime Component (Windows Phone Silverlight 8.1) <- this is DLL
C++ ProjectB ->DLL (Windows Phone Silverlight 8.1)
C++ PorjectC ->DLL (Windows Phone)  <- (WinRT 8.1)

好的，我没有任何语法问题，在线上有很多教程，例如

// In C#
[DllImport("WRCWP81SLd.dll", EntryPoint = "DllWP81SLFunc")]

// In C++
extern "C" __declspec(dllexport) int DllWP81SLFunc();

问题是，如何将dll添加到C＃项目中，如何将dll项目连接到C＃项目中，以使C＃在DLL中检测C ++函数？

我试图添加该项目的引用，如某些教程中的ppl所说的那样（它适用于C ++到C ++）

但是，当将ProjectA，ProjectB，ProjectC添加到[C＃Project-> WP8.1 Silverlight]中时

除了将[WinRuntimeComponent Silverlight8.1]添加到[WP8.1 Silverlight]外，所有操作均失败

将ProjectA，ProjectB，ProjectC添加到[C＃Project-> WP8.1 RT]

全部失败

A reference to 'DLLWP81RT' could not be added.

关于唯一被发现的一个[C＃WP8.1 Silverlight]-[C ++ Windows运行时组件Silverlight 8.1]，它在运行时崩溃了。

// declare
[DllImport("WRCWP81SLd.dll", EntryPoint = "DllWP81SLFunc", CallingConvention = CallingConvention.StdCall)]
public static extern int DllWP81SLFunc();

// crash at this line, couldn't detect the function
int w = DllWP81SLFunc(); <- crash

所以我的问题是：用C＃项目连接C ++ DLL的正确方法是什么？如何让C＃在WindowsPhone 8.1 RT / Silverlight项目上检测C ++功能？

//-------------------------------------------------------------------------------------
//-----------The beautiful devider
//-------------------------------------------------------------------------------------

对大卫·赫弗南的回答：

在[C＃WP8.1 Silverlight]项目上

尝试添加[C ++ DLL WP8.1 RT]时

Unable to add the reference to DLLWP81RT.A reference to 'DLLWP81RT' could not be added.
The method or operation is not implemented.

尝试添加[C ++ DLL WP8.1 Silverlight]时

Unable to add the reference to DLLWP81SL.A reference to 'DLLWP81SL' could not be added.
The method or operation is not implemented.

// -------------------------------------------

在[C＃WP8.1 WRT]项目中

尝试添加[C ++ DLL WP8.1 RT]作为参考时

A reference to 'DLLWP81RT' could not be added

尝试添加[C ++ DLL WP8.1 Silverlight]作为参考时

A reference to 'DLLWP81SL' could not be added

尝试添加[C ++ WindowsRuntimeComponent WP8.1]作为参考时

A reference to 'WRCWP81SL' could not be added

所以到目前为止

我只能将[C ++ WindowsRuntimeComponent WP8.1]添加到[C＃WP8.1 Silverlight]项目，但无法调用C样式函数-

An exception of type 'System.NotSupportedException' occurred in 'YYYY.DLL' but was not handled in user code
Additional information: DllImport cannot be used on user-defined methods