CODEWITHSUNDEEP
c#pointersobjectunmanagedmanaged
leon22
leon22

Reputation: 5639

Return unmanaged object pointer in C#

I have written two managed C++ wrappers for native C++ classes and I need a unmanaged object of native Class B as a return param in function of managed Wrapper A that construct native Class A!

Example:

// Wrapper A

WrapperA::WrapperA(ClassB *classB)
{
    ClassA *classA = new ClassA(classB);
    ...
}

// native c++
ClassA::ClassA(ClassB *classB)
{
    m_classB = classB; // ClassB *m_classB; in .h
    ...
}

// Wrapper B

ClassB* WrapperB::GetNativeClassB()
{
    return m_classB; // ClassB *m_classB; in .h
}


// in C#
...
WrapperB wrapperB = new WrapperB();

unsafe // need for C++ pointer
{
WrapperA wrapperA = new WrapperA(wrapperB.GetNativeClassB() ); 
// Error: is inaccessible due to its protection level 
// -> is set to public
}
...

Is there a better way without unsafe and why I get an access error ???

Thank you in advance!

greets leon22

Upvotes: 0

Views: 2362

Answers (2)

leon22
leon22

Reputation: 5639

Solution from: Pass a C++/CLI wrapper of a native type to another C++/CLI assembly

// in WrapperB
property IntPtr _classB 
{
    IntPtr get() { return IntPtr(classB); }
}

// in WrapperA
ClassB *classB = static_cast<ClassB*>(wrapperB->_classB.ToPointer());
// ... do something ...

Upvotes: 0

Marcello Faga
Marcello Faga

Reputation: 1204

  1. Protection level: i'm sure you have public defined, but what about the dll containing the symbol? Are you sure you have the last release?

  2. Unsafe: in order to use/wrap unsafe/native code as C++, the best option it is to use C++/CLI (ex Managed C++), provided starting from the Visual Studio 2005 release. just define a ref class that wraps your native/unmanaged class, that one will be directly accessible from managed code, as C#. Hint to start with Visual Studio: open a new dll CLR project from the Visual C++ section;

C++/CLI is the best solution in my opinion

Upvotes: 1

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