转换std :: vector< T>的最有效方法是什么到.NET List< U&gt ;？ [英] What is the most efficient way to convert a std::vector<T> to a .NET List<U>?

问题描述

将std :: vector转换为.NET列表的最有效方法是什么？

What is the most efficient way to convert a std::vector to a .NET List?

为了提供一些背景信息，我使用了一个非托管C ++类C ++ / CLI。 C ++ / CLI类包含一个指向C ++类的指针，每个公共方法都有一个包装器。

To give some context, I am wrapping an unmanaged C++ class with C++/CLI. The C++/CLI class holds a pointer to the C++ class and I have a wrapper for each public method.

一个方法返回一个std :: vector，因此在我的包装器中我打算返回.NET类列表。即

One method returns a std::vector, so in my wrapper I was going to return the .NET class List. I.e.

// unmanaged class
class A
{
    public:
        std::vector<int> runList();
}

// managed class
public ref class A
{
    public:
        // the below is obviously extremely inefficient
        List<UInt32> MethodA()
        {
            std::vector<unsigned int> runList = mpChannelNode->runList();
            std::vector<unsigned int>::iterator itr;

            List<UInt32> list = gcnew List<UInt32>();

            for (itr = runList.begin(); itr != runList.end(); itr++)
            {
                list.Add(*itr);
            }

            return list;
        }

    private:
        A* mpChannelNode;
}

如何提高效率？随时为.NET类推荐其他返回类型。假设我只是需要以任何形状或形式将向量有效地带入管理的世界中。

How can I make this more efficient? Feel free to recommend a different return type for the .NET class. Lets assume I just need to get that vector into managed world efficiently in any shape or form.

推荐答案

如果您真的对此担心，请改用不可验证的代码：

If you're really that concerned about it, use unverifiable code instead:

List<unsigned>^ MethodA()
{
    std::vector<unsigned> const& runList = mpChannelNode->runList();
    array<unsigned>^ ret = gcnew array<unsigned>(runList.size());
    if (runList.size())
    {
        pin_ptr<unsigned> dest = &ret[0];
        std::memcpy(dest, &runList[0], runList.size() * sizeof(unsigned));
    }
    return gcnew List<unsigned>(ret);
}

话虽如此，如果两种方式之间都存在明显差异，我会感到惊讶...

That said, I'd be surprised if there was a noticeable difference either way...

这篇关于转换std :: vector< T>的最有效方法是什么到.NET List< U&gt ;？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！