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C++/CLI编程知识点小记

article 2024/11/13 6:38:43

1.前言

本篇博文并非详细的C++/CLI教程，仅是博主就学习和实践总结的部分知识点记录。

第一次接触C++/CLI是2017年了，用C++编写底层库，C++/CLI编写wrapper层，在C#项目中进行调用，开发应用。

2.内容

C++/CLI是一种混合编程，在.NET框架下混合使用.NET和C++语言进行编程，既可以使用native C++,又可以使用managed C++(托管C++),还可以使用.NET。
这就说明在C++/CLI中可以用native C++编写代码，可以调用C++库，可以编写托管代码和类，可以使用.NET语言，一种典型的应用是作为Wrapper封装层来封装C++库的类和接口、做C++/C#类型的转换，然后在C#应用程序中调用，开发便捷易用的应用程序。
关于native C++,托管C++,CLI,CLR等概念参考托管C++、C++/CLI、CLR-腾讯云开发者社区-腾讯云
STL/CLR Library：The STL/CLR Library provides an interface similar to the C++ Standard Library containers for use with C++ and the .NET Framework common language runtime (CLR). STL/CLR is completely separate from the Microsoft implementation of the C++ Standard Library. STL/CLR is maintained for legacy support but is not kept up-to-date with the C++ standard. We strongly recommend using the native C++ Standard Library containers instead of STL/CLR whenever possible.
在C++/CLI中可以使用和C++标准库容器非常接近的容器，享受C++标准库容器的强大能力，当然不建议这种方式使用容器，建议直接使用native C++标准库；
STL/CLR Library Reference | Microsoft LearnLearn more about: STL/CLR Library Referencehttps://learn.microsoft.com/en-us/cpp/dotnet/stl-clr-library-reference?view=msvc-170
在涉及C++/C#参数转换时，可直接在C++/CLI项目中编写转换函数进行【C++到C#】或【C#到C++】的参数转换，注意基本类型（int/double/float等）不需要转换，而string、容器等需要转换；

string转换：

//返回的值需要释放内存
wchar_t *ManagedStr2UnmanagedUniStr(String^ str)
{
    IntPtr p = Marshal::StringToHGlobalUni(str);
    if (p == IntPtr::Zero)
        return(NULL);

    const wchar_t *pTemp = static_cast<const wchar_t *>(p.ToPointer());
    if (pTemp == NULL) return NULL;

    size_t  len = wcslen(pTemp) + 1;
    wchar_t *pOut = new wchar_t[len];

    wcscpy_s(pOut, len, pTemp);

    Marshal::FreeHGlobal(p);
    return(pOut);
}

//非托管字符串转托管的Unicode字符串
String ^ UnmanagedStr2ManagedUniStr(wchar_t *str)
{
    return Marshal::PtrToStringUni((IntPtr)str);
}

可编写转换函数进行C++和C#间容器类型的转换，以便于在C#中调用带有标准C++ STL容器类型参数的C++接口；或将C#传递来的容器参数转换为C++ STL容器参数，以便调用底层C++库接口实现，
```
void Convert(List<LineWrapper^>^ lines, list<Line>& cLines)
{
    if (!lines)
        return;

    for each (LineWrapper ^ line in lines)
    {
        cLines.push_back(*line->GetImplPtr());
    }
}
```

可直接在C++/CLI中编写wrapper类以便于在C#项目中使用以存在的功能强大的C++类，

public ref class LineWrapper
    {
    public:
        LineWrapper()
        {
            mImpl = new Line();
        }
        LineWrapper(const Line* impl)
        {
            mImpl = new Line(*impl);
        }
        ~LineWrapper()
        {
            delete mImpl;
        }

        property Vector3Wrapperf^ Pt0
        {
            Vector3Wrapperf^ get()
            {
                Vector3f pt = mImpl->pt0;
                return gcnew Vector3Wrapperf(pt.X, pt.Y, pt.Z);
            };

            void set(Vector3Wrapperf^ pt)
            {
                mImpl->pt0.X = pt->X;
                mImpl->pt0.Y = pt->Y;
                mImpl->pt0.Z = pt->Z;
            };
        }

        property Vector3Wrapperf^ Pt1
        {
            Vector3Wrapperf^ get()
            {
                Vector3f pt = mImpl->pt1;
                return gcnew Vector3Wrapperf(pt.X, pt.Y, pt.Z);
            };

            void set(Vector3Wrapperf^ pt)
            {
                mImpl->pt1.X = pt->X;
                mImpl->pt1.Y = pt->Y;
                mImpl->pt1.Z = pt->Z;
            };
        }

        Line* GetImplPtr()
        {
            return mImpl;
        }

    private:
        Line* mImpl;
    };

对于native C++库中的模板类，在C++/CLI项目中需要继承方式实例化模板类，从而在C#项目中使用实例化的类，

       template<typename T>
       public ref class Vector3Wrapper
       {
       public:
           static Vector3Wrapper^ BasicX = gcnew Vector3Wrapper;
           static Vector3Wrapper^ BasicY = gcnew Vector3Wrapper;
           static Vector3Wrapper^ BasicZ = gcnew Vector3Wrapper;
           static Vector3Wrapper^ Zero = gcnew Vector3Wrapper;

       public:
           property T X
           {
               void set(T x) { mImpl->X = x; }
               T get() { return mImpl->X; }
           }

           property T Y
           {
               void set(T y) { mImpl->Y = y; }
               T get() { return mImpl->Y; }
           }

           property T Z
           {
               void set(T z) { mImpl->Z = z; }
               T get() { return mImpl->Z; }
           }

           Vector3Wrapper() { mImpl = new Vector3<T>(); }
           Vector3Wrapper(const Vector3<T>* impl) { mImpl = new Vector3<T>(*impl); }
           Vector3Wrapper(T x, T y, T z) { mImpl = new Vector3<T>(x,y,z); }
           template<typename ST> Vector3Wrapper(Vector3Wrapper<ST>% other) { mImpl = new Vector3<T>(*other.mImpl); };
           virtual ~Vector3Wrapper() { delete mImpl; };

       public:
           void Normalize() { mImpl->Normalize(); };
           //  define other functions here
           

           Vector3<T>* GetImplPtr() { return mImpl; };

       private:
           Vector3<T>* mImpl;

       };

       
       public ref class Vector3Wrapperf : public Vector3Wrapper<float>
       {
       public:
           Vector3Wrapperf(float x, float y, float z) : Vector3Wrapper(x, y, z) {}
           Vector3Wrapperf(): Vector3Wrapper(){ }
           Vector3Wrapperf(const Vector3<float>* impl): Vector3Wrapper(impl){ }
           ~Vector3Wrapperf() { };

           //define other functions here
           
       };

在C++/CLI项目中同样需要提取公共函数或类，便于使用，

3.参考文章

1、从C++到C++/CLI

https://www.cnblogs.com/feisky/archive/2009/11/22/1607999.htmlhttps://www.cnblogs.com/feisky/archive/2009/11/22/1607999.html2、相关博文：

C++/CLI 总结_array^ arr = gcnew-CSDN博客文章浏览阅读1.2k次，点赞5次，收藏14次。在Windows上，除非我们必须得用C++来写界面，否则我会选择避免，避免学习和使用MFC。替代的方案是用C#来做界面，然后用C++/CLI来连接C#和Native C++。那么问题来了，C++/CLI是何方神圣？　　百度上对于C++/CLI是这么说的——“C++/CLI是静态C++对象模型到CLI的动态组件对象编程模型的捆绑。简而言之就是如何用C++在·NET中编程，而不是C#或Visual B..._array^ arr = gcnewhttps://blog.csdn.net/weixin_29130507/article/details/802673293、微软官方说明文档：

Generic Classes (C++/CLI) | Microsoft LearnLearn more about: Generic Classes (C++/CLI)https://learn.microsoft.com/en-us/cpp/extensions/generic-classes-cpp-cli?view=msvc-170.NET programming with C++/CLI | Microsoft LearnLearn how to use C++/CLI to create .NET apps and components in Visual Studio.https://learn.microsoft.com/en-us/cpp/dotnet/dotnet-programming-with-cpp-cli-visual-cpp?view=msvc-170Generic Functions (C++/CLI) | Microsoft LearnLearn more about: Generic functions (C++/CLI)https://learn.microsoft.com/en-us/cpp/extensions/generic-functions-cpp-cli?view=msvc-170

4、【原】C++与C#对常用数据结构封装的对比（STL vs System.Collections.Generic）https://www.cnblogs.com/cocoaleaves/archive/2009/05/30/1492269.html

5、Convert all values from dictionary into list in C++/CLIc++ cli - Convert all values from dictionary into list in C++/CLI - Stack Overflow

6、c++ - Cpp/Cli Convert std::map to .net dictionary - Stack Overflow

7、C++/CLI封装原生C++库供.NET项目调用-CSDN博客

8、Use C++ CLI template class in C#
.net - Use C++ CLI template class in C# - Stack Overflow

9、C++/CLI: functions inherited from template class are not visible in C#

.net - C++/CLI: functions inherited from template class are not visible in C# - Stack Overflow

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