我有产生矩形是有趣的名单C ++函数。我希望能够获得该列表出来的C ++库，并返回到C＃应用程序正在调用它。

I have a C++ function that produces a list of rectangles that are interesting. I want to be able to get that list out of the C++ library and back into the C# application that is calling it.

到目前为止，我编码的矩形像这样：

So far, I'm encoding the rectangles like so:

struct ImagePatch{ 
   int xmin, xmax, ymin, ymax;
}

和再编码的一些载体：

void MyFunc(..., std::vector<int>& rectanglePoints){
   std::vector<ImagePatch> patches; //this is filled with rectangles
   for(i = 0; i < patches.size(); i++){
       rectanglePoints.push_back(patches[i].xmin);
       rectanglePoints.push_back(patches[i].xmax);
       rectanglePoints.push_back(patches[i].ymin);
       rectanglePoints.push_back(patches[i].ymax);
   }
}

与C＃交互的头看起来像（和工程一堆其他功能）：

The header for interacting with C# looks like (and works for a bunch of other functions):

extern "C" {
    __declspec(dllexport) void __cdecl MyFunc(..., std::vector<int>& rectanglePoints);
}

是否有一些关键字或其他的事情，我可以做的就是这组矩形呢？我发现此文编组在C＃中的对象，但似乎这样太复杂，太underexplained。是整数的矢量正确的方式来做到这一点，还是有一些其他的诀窍或方法？

Are there some keywords or other things I can do to get that set of rectangles out? I found this article for marshalling objects in C#, but it seems way too complicated and way too underexplained. Is a vector of integers the right way to do this, or is there some other trick or approach?

推荐答案

STL是一个C ++的特定库，所以你不能直接把它整个作为一个对象为C＃。

The STL is a C++ specific library, so you cant directly get it across as one object to C#.

这是保证大约性病的一件事::矢量是＆安培; v [0]指向的第一个元素和所有元素位于线性内存中（换言之，其就像在内存方面的C数组布局）

The one thing that is guaranteed about std::vector is that &v[0] points to the first element and all the elements lie linearly in memory (in other words, its just like a C array in terms of memory layout)

所以名帅作为数组为int的......这应该不难 - 有很多在网络上的例子

So marshal as array of int... which shouldn't be hard - There are lot of examples on the web.

添加

假设你只能在C ++中的数据传递到C＃：

Assuming you only pass the data from C++ to C# :

C＃中不能处理的C ++矢量对象，所以不要尝试通过引用传递的：不是你的C ++ code必须返回一个指向整数数组...

C# cannot handle a C++ vector object, so do not try passing it by reference : Instead your C++ code must return a pointer to an array of ints...

如果您不打算使用多个线程此功能，您可以使用静态存储：

If you are not going to be using this function from multiple threads, you can use static storage :

int *getRects(bool bClear)
{
    static vector<int> v; // This variable persists across invocations
    if(bClear)
    {
        v.swap(vector<int>());
    }
    else
    {
        v.clear();
        // Fill v with data as you wish
    }

    return v.size() ? &v[0] : NULL;
}

通话getRects（真），如果返回的数据的大小显著，让你释放v内存。

call getRects(true) if the returned data is significant in size, so you release the memory in v.

为了简单起见，而不是传递出的矢量数据的大小也一样，只是把警戒值时结束（如说-1），所以C＃code可以检测数据终止的位置。

For simplicity, instead of passing out the size of the vector data too, just put a sentinel value at the end (like say -1) so the C# code can detect where the data ends.