unable to load c dll module in Lua - c++

Question

I try to test loading a c++ dll module in Lua using "require", below is the c++ module file
#include <stdio.h>
#include <iostream>
extern "C" {
#include "lua/lualib.h"
#include "lua/lauxlib.h"
#include "lua/lua.h"
__declspec(dllexport) int luaopen_mylib(lua_State* L);
}
using namespace std;
static int libFunc1(lua_State* L)
{
int n = lua_gettop(L);
printf("in myfunc stack, arg number: %d\n", n);
if (lua_isstring(L, -1))
{
std::cout << lua_tostring(L, -1) << std::endl;
}
else
{
std::cout << "invalid arg" << std::endl;
}
return 1;
}
static const struct luaL_Reg mylib[] = {{"func1", libFunc1}, {NULL, NULL}};
int luaopen_mylib(lua_State* L)
{
cout << "loading my lib" << endl;
luaL_newlib(L, mylib);
return 1;
}
I compiled this cpp file into dll using g++ in msys:
g++ -c -o mylib.o mylib.cpp
g++ -shared -o mylib.dll mylib.o -Llua -llua5.3.0
until now everything work fine, and I got the mylib.dll file too. but when I try to load the module, I got the error msg:
> require("mylib")
error loading module 'mylib' from file '.\mylib.dll':
找不到指定的程序。
stack traceback:
[C]: in ?
[C]: in function 'require'
stdin:1: in main chunk
[C]: in ?
the Chinese characters above mean:
The specified function could not be found.
I think the "specified function" mean the "luaopen_mylib", but the cpp file do have the function:luaopen_mylib, WHAT IS GOING WRONG?

Answer 1

It might be some name mangling problem. Try:
extern "C"
{
int luaopen_mylib(lua_State* L)
{
cout << "loading my lib" << endl;
luaL_newlib(L, mylib);
return 1;
}
}