C++/CLI 包装器实现错误

Question

我一直在尝试在以下 link 中使用 C++/CLI 包装器方案。

注意：在上周我进行的所有搜索中，以下项目是被引用最多的提供可行解决方案的项目。
http://pragmateek.com/using-c-from-native-c-with-the-help-of-ccli-v2/

下面的项目是我尝试 link 接受 Win32 Dll 的第 3 方应用程序。我们的目标是 link 将 Win32 Dll 转换为托管 C# DLL，其中的函数应该更易于编写和维护。

但是，我将运行保留为以下错误的变体。

Error   C2664   'std::basic_string<char,std::char_traits<char>,std::allocator<char>>::basic_string(std::initializer_list<_Elem>,const std::allocator<char> &)' : cannot convert argument 1 from 'System::String ^' to 'const std::basic_string<char,std::char_traits<char>,std::allocator<char>> &' Main_interface  

Error (active)  E0415   no suitable constructor exists to convert from "System::String ^" to "std::basic_string<char, std::char_traits<char>, std::allocator<char>>"    Main_interface

我的 C# 库：MainUtilities.dll

//Main_Utility.cs

public class MainUtilities
{
    public string GetRevision(string CurrentRev)
    {
        return CurrentRev + "_rev";
    }
}

Main_Interface.h

#pragma once

#define DLL_EXP extern "C" __declspec(dllexport)
DLL_EXP void GetRevision(char* data_in, char *data_out);

class QFUtilitiesWrapperPrivate;

#ifdef BUILDINGQFUTILITIES
#define DLL_EXP_WRAP __declspec(dllexport)
#else
#define DLL_EXP_WRAP __declspec(dllimport)
#endif

#include <string>

class DLL_EXP_WRAP QF_UtilitiesWrapper
{
private: static QFUtilitiesWrapperPrivate* _private;

public: QF_UtilitiesWrapper();

public: ~QF_UtilitiesWrapper();

public: static std::string GetRevisionFunc(const char* rev);

};

Main_Interface.cpp

#include "stdafx.h"
#include "Main_Interface.h"
#include <msclr\auto_gcroot.h>
#using "MainUtilities.dll"
using namespace System::Runtime::InteropServices; // Marshal


class QFUtilitiesWrapperPrivate
{
public: msclr::auto_gcroot<MainUtilities^> main_Utilities;
};

QF_UtilitiesWrapper::QF_UtilitiesWrapper()
{
    _private = new QFUtilitiesWrapperPrivate();
    _private->main_Utilities = gcnew MainUtilities();
}

DLL_EXP void GetRevision(char* data_in, char *data_out)
{
    std::string s_b = QF_UtilitiesWrapper::GetRevisionFunc(data_in);
    strcpy_s(data_out, 100, s_b.c_str());
}

std::string QF_UtilitiesWrapper::GetRevisionFunc(const char* data_in)
{
    return _private->main_Utilities->GetRevision(gcnew System::String(data_in));
} //** ERROR ^^^^^^  ** 

QF_UtilitiesWrapper::~QF_UtilitiesWrapper()
{
    delete _private;
}

请注意错误发生在：'GetRevisionFunc'

编辑：好的 - 我做了以下更改：

//Main_Interface.h

private:  QFUtilitiesWrapperPrivate* _private;  // no longer static
public: const char* GetRevisionFunc(const char* rev); //function now: const char*

//Main_Interface.cpp

DLL_EXP void GetRevision(char* data_in, char *data_out)
{
    data_out = QF_UtilitiesWrapper::GetRevisionFunc(data_in);
  // ** ERROR ^^^^^^^^^^ **
}

const char* QF_UtilitiesWrapper::GetRevisionFunc( char* rev) // now: const char*
{
    System::String^ managedCapi = _private->main_Utilities->GetRevision(gcnew System::String(rev));
    return (const char*)Marshal::StringToHGlobalAnsi(managedCapi).ToPointer();
}

现在我要解决以下错误：

Error C2352 'QF_UtilitiesWrapper::GetRevisionFunc' : illegal call of non-static member function

Error (active) E0245 a nonstatic member reference must be relative to a specific object

Answer 1

好吧，您必须整理类型，这在 C++/CLI 中没有为您完成。你有一个 System::String^ 但你想 return 它作为一个 std::string，所以你必须编组它：

std::string QF_UtilitiesWrapper::GetRevisionFunc(const char* data_in)
{
    auto str = _private->main_Utilities->GetRevision(gcnew System::String(data_in));
    return msclr::interop::marshal_as<std::string>(str);
}

有关更多详细信息，请查看 the docs。

您的 QF_UtilitiesWrapper 也持有 _private 作为 static 成员，您在构造函数/析构函数中设置和删除它。这将泄漏内存并可能导致意外行为。

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