CCLI Mixing Native and Managed Code

C++/CLI Mixing Native and Managed Code

One of the big advantages of C++/CLI is mixing native and managed code. Using native code from C# is done with a mechanism known as platform invoke. Platform invoke is discussed in Chapter 23, “COM Interoperability.” Using native code from C++/CLI is known with the term It just works.

In a managed class, you can use both native and managed code, as you can see here. The same is true for a native class. You can mix native and managed code as well within a method.

  #pragma once #include <iostream>      // include this header file for cout using namespace std;     // the iostream header defines the namespace std using namespace System; public ref class Managed { public:    void MixNativeAndManaged()    {       cout << "Native Code" << endl;       Console::WriteLine("Managed Code");    } }; 

In a managed class, you can also declare a field of a native type or a pointer to a native type. Doing the same the other way around is not possible to accomplish directly. You must take care that an instance of a managed type can be moved by the garbage collector when cleaning up memory.

For using managed classes as member within native classes, C++/CLI defines the keyword gcroot, which is defined in the header file gcroot.h. gcroot wraps a GCHandle that keeps track of a CLR object from a native reference.

  #pragma once #include "gcroot.h" using namespace System; public ref class Managed { public:    Managed() { }    void Foo()    {    Console::WriteLine("Foo");    } }; public class Native { private:    gcroot<Managed^> m_p; public:    Native()    {       m_p = gcnew Managed();    }    void Foo()    {       m_p->Foo();    } };