C++DLL到C#错误:“；尝试读取或写入受保护的内存.这通常表示其他内存已损坏&”；

我有两个DLL。一个是PrimaryDLL.dll，另一个是DLLLrap.dll。PrimaryDLL有一个对象，一个名为DiversifyKeyset的函数，在类构造函数中标记为：

static PRIMARYDLL_API std::string DiversifyKeyset(std::string Key1, std::string Key2, std::string Key3);

这里是定义的方法：

    std::string tKeyset::DiversifyKeyset(std::string Key1, std::string Key2, std::string Key3)
{
    tKeyset* keyset = new tKeyset();
    keyset ->Key1 = "12345678";
    keyset ->Key2 = "23456789";
    keyset ->Key3 = "34567890";
    //return keyset --eventually I want to return this
    return 0;
}

我的DLLLrap.dll在其.cpp文件中这样调用此函数：

cout << "Here is what is returned:  " <<
firstDllLayer::tKeyset::DiversifyKeyset(a,b,c) << endl;

现在，所有这些都编译得很好，库也构建好了。当我调用C#代码来调用第二个DLLLrap.dll时，我出现了错误。我收到了错误：

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

因此，我一直在绞尽脑汁，想为什么这不起作用。我承受着很大的压力，但似乎不明白为什么我会收到这个记忆写入错误。

因此，为了帮助我提供我的代码。

我的C++PrimaryDLL.h文件：

#pragma once
#include "stdafx.h"
#include <string>
#include <stdexcept>
extern "C"{
#ifdef PRIMARYDLL_EXPORT
    #define PRIMARYDLL_API __declspec(dllexport) 
#else
    #define PRIMARYDLL_API __declspec(dllimport)  
#endif

namespace firstDllLayer
{
class tKeyset
{

public:
    tKeyset();
    std::string Key1;
    std::string Key2;
    std::string Key3;
    tKeyset(std::string _key1, std::string _key2, std::string _key3);
    static PRIMARYDLL_API std::string DiversifyKeyset(std::string Key1, std::string Key2, std::string Key3);

};
tKeyset::tKeyset()
{
    Key1 = "";
    Key2 = "";
    Key3 = "";
}
tKeyset::tKeyset(std::string _Key1, std::string _Key2, std::string _Key3)
{
    Key1 = _Key1;
    Key2 = _Key2;
    Key3 = _Key3;
}

}
}

这是PrimaryDll.cpp文件：

// PrimaryDll.cpp : Defines the exported functions for the DLL application.
//
#include "stdafx.h"
#include "PrimaryDll.h"
#include <stdexcept>
#include <string>
using namespace std;
namespace firstDllLayer
{
    tKeyset* MasterKeyset = new tKeyset("1234","5678","0910");
    std::string tKeyset::DiversifyKeyset(std::string Key1, std::string Key2, std::string Key3)
{
    tKeyset* keyset = new tKeyset();
    keyset ->Key1 = "12345678";
    keyset ->Key2 = "23456789";
    keyset ->Key3 = "34567890";
    //return Keyset; -eventually I would like to return this
    return 0;
}
}

这是我的DLLWrap.h文件：

#pragma once
#include "stdafx.h"
#include "Primary.h"
#include <stdexcept>
#include <string>
extern "C"{
#ifdef DLLWRAPDLL_EXPORT
    #define DLLWRAP_API __declspec(dllexport) 
#else
    #define DLLWRAP_API __declspec(dllimport)  
#endif
namespace MyFunc
{
    class MyCall
        {
        public:
            static DLLWRAP_API std::string DiversifyKeysetCall(std::string a,std::string b,std::string c);
    };
}
}

DLLFrap.pp文件：

// DLLWrap.cpp : Defines the exported functions for the DLL application.
//

#include "stdafx.h"
#include "PrimaryDll.h"
#include <stdexcept>
#include "DLLWrap.h"
#include <iostream>
#include <string>
using namespace std;
namespace MyFunc
{
    std::string MyCall::DiversifyKeysetCall(std::string a,std::string b,std::string c)
    {
            /*cout << "Here is what is returned:  " <<
                firstDllLayer::tKeyset::DiversifyKeyset(a,b,c) << endl;
            return 0;*/
        cout << "Here is what is returned:  " <<
                firstDllLayer::tKeyset::DiversifyKeyset(a,b,c) << endl;
            return 0;           
    }
}

最后是C#程序.cs文件：

// Marshal.cs
using System;
using System.Runtime.InteropServices;
class PlatformInvokeTest
{    public class DllHelper
    {
        [DllImport(@"C:'Users'user'Documents'Visual Studio 2010'Projects'KeyDll'Debug'DLLWrap.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "?DiversifyKeysetCall@MyCall@MyFunc@@SA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V34@00@Z")]
        public static extern string DiversifyKeysetCall(string a, string b, string c);
    }
    static void Main()
    {    
        try
        {
            DllHelper.DiversifyKeysetCall("1234","5678","0910");           
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
        }
}

在我的PrimaryDLL.cpp文件中，我最终想返回对象，但因为它在如何引用指针以及何时离开：方面太令人困惑了

return keyset; 

Uncomment我收到错误，它无法从对象类型转换为字符串类型。

因此，如果有任何帮助，我将非常感谢为什么我收到"试图读取或写入受保护的内存。这通常表明其他内存已损坏"错误。

谨致问候。