C#与C++ dll之间传递字符串string wchar_t* char* IntPtr问题

extern "C" _declspec(dllexport)const wchar_t* Diagnoser(wchar_t* inputText)
{
    delete diagnoser;
    diagnoser = new FireEye::Diagnoser();
    diagnoser->diagnose(inputText);
    diagnoser->report();
    return diagnoser->reportText.c_str();
}

//声明
[DllImport("FireEyeDll.dll", CharSet = CharSet.Unicode , CallingConvention = CallingConvention.Cdecl)]
//public static extern string Diagnoser(string inputText); //.net 4.0
public static extern IntPtr Diagnoser(string inputText);
 
 
 
//调用
//outputBox.Text = Diagnoser(inputBox.Text); //.net 4.0
IntPtr outPtr = Diagnoser(inputBox.Text);
outputBox.Text = Marshal.PtrToStringUni(outPtr);

DLL_API_LR void GetAuthInfo(char* strCode);

void GetAuthInfo(int inPrama1, char *inParam2, int outParam1, char *outParam2)
{
    char buff[2048];
    memset(buff, 0, 2048);
    std::ifstream inFile("license.lr", std::ios::binary);
    if (inFile.fail())
    {
        return;
    }
    else
    {
        inFile.read(buff, sizeof(temp));
        inFile.close();
    }
    memcpy(outParam2, buff, outParam2.length());
    string strCode=outParam2；
    outParam1=strCode.length()；
}

[DllImport("Lib_LR.dll", EntryPoint = "GetAuthInfo", CallingConvention = CallingConvention.Cdecl)]
public static extern void GetAuthInfo(ref int InParam1, string nInPrama2, StringBuilder strCode);

int inParam1=0;
int outParam1=0;
string inParam2="测试";
StringBuilder outParam2= new StringBuilder(1024);
//注意：调用函数的时候，int型的出口参数要加ref，出口字符串参数要声明StringBuilder类型
GetAuthInfo(inParam1，inParam2，ref outParam1,outParam2);