C#调用 C++

// testdll3.cpp : Defines the entry point for the DLL application.
//

#include "stdafx.h"

BOOL APIENTRY DllMain( HANDLE hModule,
                       DWORD ul_reason_for_call,
                       LPVOID lpReserved
      )
{
    return TRUE;
}

extern "C" __declspec(dllexport) int add(int * a,int * b)
{
return *a + *b;
}

Ｃ＃中的调用方法：

[DllImport("testdll3.dll", EntryPoint = "add", CharSet = CharSet.Unicode)]
        private extern static int cadd(out int a, out int b);

int a = 1;
int b = 2;
int re = cadd(out a, out b);／／成功返回3