blocks|key|1682883|text|在C#代码中无法直接使用C%2B%2B类。您可以以间接方式使用PInvoke来访问您的类型。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1682884|基本模式是，对于类Foo中的每个成员函数，创建一个关联的非成员函数，该函数调用成员函数。|1682885|class+Foo+{
public:
++int+Bar();
};
extern+"C"+Foo*+Foo_Create()+{+return+new+Foo();+}
extern+"C"+int+Foo_Bar(Foo*+pFoo)+{+return+pFoo->Bar();+}
extern+"C"+void+Foo_Delete(Foo*+pFoo)+{+delete+pFoo;+}|code-block|syntax|javascript|1682886|现在是将这些方法PInvoking到C#代码中的问题了|1682887|[DllImport("Foo.dll")]
public+static+extern+IntPtr+Foo_Create();

[DllImport("Foo.dll")]
public+static+extern+int+Foo_Bar(IntPtr+value);

[DllImport("Foo.dll")]
public+static+extern+void+Foo_Delete(IntPtr+value);|1682888|缺点是您需要传递一个笨拙的IntPtr，但是围绕这个指针创建一个C#包装类来创建一个更有用的模型是一件比较简单的事情。|1682889|即使您不拥有这段代码，您也可以创建另一个DLL来包装原始DLL并提供一个小的PInvoke层。|1682890|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

There is no way to directly use a C++ class in C# code. You can use PInvoke in an indirect fashion to access your type. 

The basic pattern is that for every member function in class Foo, create an associated non-member function which calls into the member function. 

<pre><code>class Foo {
public:
 int Bar();
};
extern "C" Foo* Foo_Create() { return new Foo(); }
extern "C" int Foo_Bar(Foo* pFoo) { return pFoo-&gt;Bar(); }
extern "C" void Foo_Delete(Foo* pFoo) { delete pFoo; }
</code></pre>

Now it's a matter of PInvoking these methods into your C# code

<pre><code>[DllImport("Foo.dll")]
public static extern IntPtr Foo_Create();

[DllImport("Foo.dll")]
public static extern int Foo_Bar(IntPtr value);

[DllImport("Foo.dll")]
public static extern void Foo_Delete(IntPtr value);
</code></pre>

The downside is you'll have an awkward IntPtr to pass around but it's a somewhat simple matter to create a C# wrapper class around this pointer to create a more usable model.

Even if you don't own this code, you can create another DLL which wraps the original DLL and provides a small PInvoke layer.

blocks|key|1683129|text|您可能需要编写一个中间DLL+(也许是在C%2B%2B中)来为您处理此问题并公开所需的接口。您的DLL将负责加载第三方DLL，创建此C%2B%2B对象的实例，并根据需要通过您设计的任何应用程序接口公开其成员函数。然后使用P/Invoke获取API并干净利落地操作对象。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1683130|注意:对于DLL的API，请尝试将数据类型限制为基本类型(long、int、char*等)。以防止模块边界问题。|1683131|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

You may need to write an intermediary DLL (in C++, perhaps) that handles this for you and exposes the interface you need. Your DLL would be in charge of loading the 3rd party DLL, creating an instance of this C++ object, and exposing its member functions as needed via whatever API you design. You would then use P/Invoke to get at your API and cleanly manipulate the object.

Note: For the API of your DLL, try keeping the data types limited to primitives (long, int, char*, etc.) to prevent module boundary issues.

blocks|key|1683171|text|我同意JaredPar的观点。不能在托管代码中创建非托管类的实例。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1683172|另一件事是-如果您可以在托管C%2B%2B中重新编译DLL或使用它创建COM组件，将会容易得多。|1683173|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

I agree with JaredPar.
Creating instances of unmanaged classes in managed code should not be possible.

Another thing is - if you could recompile the DLL in managed C++ or make a COM component out of it, it would be much easier/

blocks|key|1683206|text|Here是一个如何从VB调用C%2B%2B类方法的示例-对于C#，您只需在步骤4中重写示例程序。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1683207|entityMap|0|LINK|mutability|MUTABLE|url|http://www.codeproject.com/KB/DLL/XDllPt3.aspx^0|0|4|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

<a href="http://www.codeproject.com/KB/DLL/XDllPt3.aspx" rel="noreferrer">Here</a> is a sample how to call C++ class method from VB - for C# you only have to rewrite the sample program in Step 4.

blocks|key|1467958|text|为此，我在非托管C%2B%2B动态链接库周围创建了一个瘦托管C%2B%2B包装器。托管包装包含“代理”类，这些类包装了公开.NET应用程序所需接口的非托管代码。这有点重复工作，但它允许在正常环境中进行非常无缝的操作。在某些情况下(例如ASP.NET)，依赖关系确实会变得更加棘手，但您可能不会遇到这种情况。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1467959|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

The way I've done this is by creating a thin Managed C++ wrapper around my unmanaged C++ DLL. The managed wrapper contains "proxy" classes that wrap around the unmanaged code exposing the interface that's needed by the .NET application.
This is a bit of double work but it allows quite seamless operation in normal environments. Things do get trickier with dependencies in some circumstances (such as ASP.NET) but you will probably not run into that.

blocks|key|1683300|text|封送C%2B%2B类并使用PInvoke|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1683301|C%2B%2B代码，类名.h|1683302|class+__declspec(dllexport)+CClassName
{
+public:
++++CClassName();
++++~CClassName();
++++void+function();

};|code-block|syntax|javascript|1683303|C%2B%2B代码，ClassName.cpp|1683304|CClassName::CClassName()
{
}

CClassName::~CClassName()
{
}

void+CClassName::function()
{
++++std::cout+<<+"Bla+bla+bla"+<<+std::endl;

}|1683305|C%2B%2B代码，调用者函数的ClassNameCaller.h文件|1683306|#include+"ClassName.h"++++++

#ifdef+__cplusplus
extern+"C"+{
#endif

extern+__declspec(dllexport)+CClassName*+CreateClassName();

extern+__declspec(dllexport)+void+DisposeClassName(CClassName*+a_pObject);

extern+__declspec(dllexport)+void+function(CClassName*+a_pObject);


#ifdef+__cplusplus
}
#endif|1683307|C%2B%2B代码，调用者函数的ClassNameCaller.cpp文件|1683308|#include+"ClassNameCaller.h"


CClassName*+CreateClassName()
{
++++return+new+CClassName();
}

void+DisposeClassName(CClassName*+a_pObject)
{
++++if(a_pObject!=+NULL)
++++{
++++++++delete+a_pObject;
++++++++a_pObject=+NULL;
++++}
}

void+function(CClassName*+a_pObject)
{
++++if(a_pObject!=+NULL)
++++{
++++++++a_pObject->function();
++++}
}|1683309|C#代码|1683310|[DllImport("ClassNameDll.dll")]
static+public+extern+IntPtr+CreateClassName();

[DllImport("ClassNameDll.dll")]
static+public+extern+void+DisposeClassName(IntPtr+pClassNameObject);

[DllImport("ClassNameDll.dll")]
static+public+extern+void+CallFunction(IntPtr+pClassNameObject);

//use+the+functions
IntPtr+pClassName+=+CreateClassName();

CallFunction(pClassName);

DisposeClassName(pClassName);

pClassName+=+IntPtr.Zero;+|1683311|entityMap^0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|13|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|16|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|17|8|@]|9|@]|A|$]]|$1|S|3|T|5|F|7|18|8|@]|9|@]|A|$G|H]]|$1|U|3|V|5|6|7|19|8|@]|9|@]|A|$]]|$1|W|3|X|5|F|7|1A|8|@]|9|@]|A|$G|H]]|$1|Y|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|Z|$]]

<h2>Marshal C++ Class and use the PInvoke</h2>

C++ Code ,ClassName.h

<pre><code>class __declspec(dllexport) CClassName
{
 public:
 CClassName();
 ~CClassName();
 void function();

};
</code></pre>

C++ Code, ClassName.cpp

<pre><code>CClassName::CClassName()
{
}

CClassName::~CClassName()
{
}

void CClassName::function()
{
 std::cout &lt;&lt; "Bla bla bla" &lt;&lt; std::endl;

}
</code></pre>

C++ Code, ClassNameCaller.h file for the caller function

<pre><code>#include "ClassName.h" 

#ifdef __cplusplus
extern "C" {
#endif

extern __declspec(dllexport) CClassName* CreateClassName();

extern __declspec(dllexport) void DisposeClassName(CClassName* a_pObject);

extern __declspec(dllexport) void function(CClassName* a_pObject);


#ifdef __cplusplus
}
#endif
</code></pre>

C++ Code, ClassNameCaller.cpp file for the caller function 

<pre><code>#include "ClassNameCaller.h"


CClassName* CreateClassName()
{
 return new CClassName();
}

void DisposeClassName(CClassName* a_pObject)
{
 if(a_pObject!= NULL)
 {
 delete a_pObject;
 a_pObject= NULL;
 }
}

void function(CClassName* a_pObject)
{
 if(a_pObject!= NULL)
 {
 a_pObject-&gt;function();
 }
}
</code></pre>

C# code

<pre><code>[DllImport("ClassNameDll.dll")]
static public extern IntPtr CreateClassName();

[DllImport("ClassNameDll.dll")]
static public extern void DisposeClassName(IntPtr pClassNameObject);

[DllImport("ClassNameDll.dll")]
static public extern void CallFunction(IntPtr pClassNameObject);

//use the functions
IntPtr pClassName = CreateClassName();

CallFunction(pClassName);

DisposeClassName(pClassName);

pClassName = IntPtr.Zero; 
</code></pre>

I have a dll that was written in c++, I need to use this dll in my c# code. After searching I found that using P/Invoke would give me access to the function I need, but these functions are defined with in a class and use non-static private member variables. So I need to be able to create an instance of this class to properly use the functions. How can I gain access to this class so that I can create an instance? I have been unable to find a way to do this. 

I guess I should note that the c++ dll is not my code.

using a class defined in a c++ dll in c# code

我有一个用c++写的动态链接库，我需要在我的c#代码中使用这个动态链接库。在搜索之后，我发现使用P/Invoke可以访问我需要的函数，但是这些函数是在一个类中使用定义的，并且使用非静态的私有成员变量。所以我需要能够创建这个类的一个实例来正确地使用这些函数。怎样才能访问这个类，以便创建一个实例？我一直无法找到一种方法来做...

问在c#代码中使用c++ dll中定义的类
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