朋友写的例子，先保存这里，回头也许需要。

cpptest.lua 
local mylib = require "mylib"
print(mylib.add(10))
[root@dev1 lua]# cat mylib.cpp
#include <iostream>

using namespace std;

#ifdef __cplusplus
extern "C"
{
#endif

#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>

int luaopen_mylib(lua_State*);

#ifdef __cplusplus
}
#endif

int add(lua_State *state)
{
    int n = lua_gettop(state);
    int sum = 0;
    for (int i = 0; i < n; ++i)
    {
        sum += lua_tonumber(state, i+1);
    }
    
    if (n != 0)
    {
        lua_pushnumber(state, sum);
        return 1;
    }
    return 0;
}

const luaL_Reg lib[] =
{
    {"add", add},
    {nullptr, nullptr}
};

int luaopen_mylib(lua_State *state)
{
    luaL_register(state, "mylib", lib);
    return 1;
}

[root@dev1 lua]# lua cpptest.lua
10

C++的例子

[root@dev1 test2]# ll
总用量 24
-rw-r--r--. 1 root root 69 10月 19 23:44 cpptest.lua
-rw-r--r--. 1 root root 1685 10月 19 23:42 mylib.cpp
-rwxr-xr-x. 1 root root 14224 10月 19 23:42 TestLua.so

[root@dev1 test2]# cat cpptest.lua
require "TestLua"
c = TestLua()
print("add x + y = " .. c:cadd(4,5))
[root@dev1 test2]# cat mylib.cpp

#include <iostream>
using namespace std;

#ifdef __cplusplus
extern "C"
{
#endif

#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>

int luaopen_TestLua(lua_State*);

#ifdef __cplusplus
}
#endif

int add(lua_State *state)
{
    int n = lua_gettop(state);
    int sum = 0;
    for (int i = 0; i < n; ++i)
    {
        sum += lua_tonumber(state, i+1);
    }
    
    if (n != 0)
    {
        lua_pushnumber(state, sum);
        return 1;
    }
    return 0;
}

class TestLua
{
public:
    TestLua() {}
    virtual ~TestLua() {}
    int cadd(int x, int y)
    {
        cout << "x + y = " << (x+y) << endl;
        return x + y;
    }
};

static int createTestLua(lua_State *state)
{
    *(TestLua**)lua_newuserdata(state, sizeof(TestLua*)) = new TestLua();
    luaL_getmetatable(state, "TestLua");
    lua_setmetatable(state, -2);
    return 1;
}

static int destroyTestLua(lua_State *state)
{
    delete *(TestLua**)lua_topointer(state, 1);
    return 0;
}

static int callAdd(lua_State *state)
{
    TestLua *pT = *(TestLua**)lua_topointer(state, 1);
    lua_pushnumber(state, pT->cadd(lua_tonumber(state, 2), lua_tonumber(state, 3)));
    return 1;
}

int luaopen_TestLua(lua_State *state)
{
    lua_pushcfunction(state, createTestLua);
    lua_setglobal(state, "TestLua");

    luaL_newmetatable(state, "TestLua");
    lua_pushstring(state, "__gc");
    lua_pushcfunction(state, destroyTestLua);
    lua_settable(state, -3);
    lua_pushstring(state, "__index");
    lua_pushvalue(state, -2);
    lua_settable(state, -3);

    lua_pushstring(state, "cadd");
    lua_pushcfunction(state, callAdd);
    lua_settable(state, -3);
    lua_pop(state, 1);
    
    return 1;
}

[root@dev1 test2]# lua cpptest.lua
x + y = 9
add x + y = 9

遇到的错误

[root@dev1 test2]# gcc -Wall -shared -fPIC -o ]TestLua.so -I/usr/local/openresty/luajit/include/luajit-2.1/ -L/usr/lib64/ -llua-5.1 mylib.cpp

解决办法

The problem is most likely caused by a missing libstdc++.so.6 on your machine.
Check if you have libstdc++.so.6 on your machine using .
find /usr/ -name libstdc++.so.6
If not, then you should be able to install it using: apt-get install libstdc++6