How do I convert a cli::array to a native array from native code?

问题:

I'm writing a native wrapper around a managed component written in C++\CLI.

I have the following function in managed code:

array<Byte>^ Class::Function(); 

I want to expose this function from a native C++ class with the following signature:

shared_array<unsigned char> Class::Function(); 

I've gotten as far as calling the managed function from native code, but I'm not sure how to safely copy the managed array into an unmanaged one.

gcroot<cli::array<System::Byte>^> managedArray = _managedObject->Function(); 

回答1:

There are two usual approaches:

1. Perform the marshaling with native code, which requires use of pin_ptr<>:

   boost::shared_array<unsigned char> convert(array<unsigned char>^ arr) {     boost::shared_array<unsigned char> dest(new unsigned char[arr->Length]);     pin_ptr<unsigned char> pinned = &arr[0];     unsigned char* src = pinned;     std::copy(src, src + arr->Length, dest.get());     return dest; } 

2. Perform the marshaling with managed code, which requires use of the Marshal class:

   boost::shared_array<unsigned char> convert(array<unsigned char>^ arr) {     using System::Runtime::InteropServices::Marshal;      boost::shared_array<unsigned char> dest(new unsigned char[arr->Length]);     Marshal::Copy(arr, 0, IntPtr(dest.get()), arr->Length);     return dest; } 

Generally I would prefer the latter approach, as the former can hinder the GC's effectiveness if the array is large.

回答2:

Take a look at pin_ptr, it lets you pass address of a managed class to an unmanaged function.

文章来源: How do I convert a cli::array to a native array from native code?