C++生成DLL给C#调用

1、添加C++动态链接库（DLL）

2、添加头文件 test.h

#ifndef TEST_H
#define TEST_H

// 添加要在此处预编译的标头
#include "framework.h"

#endif //TEST_H


extern "C" _declspec(dllexport) int  GetTxtStr(char* in_str, char* out_str);

2、添加cpp文件 test.cpp

int GetTextStr(char* in_str,char* out_str){
          char buff[1024];
          memset(buff, 0, sizeof(buff));
          char *test = "test"
           
           strcpy(instr,buff);
           strcat(buff,test2);
          
           strcpy(out_str,buff);

          return TRUE
           
}

3、在C#项目里如下

  [DllImport("test.dll", EntryPoint = "GetTextStr", CallingConvention = CallingConvention.Cdecl)]
    static extern int GetTextStr(string in_str, [MarshalAs(UnmanagedType.LPStr)] StringBuilder out_str);

    static void Main(string[] args)
    {
        StringBuilder str = StringBuilder();

        GetTextStr("123456", str);

        Console.WriteLine(str);

    }