(Lua) C++ 寫函式，Lua 呼叫使用

C++ 裡頭寫一個 Function 但是透過 Lua 提供input參數並且回傳結果給Lua 輸出的辦法。

Lua 檔案

local ave, sum = average(22, 20, 45)
print("ave : ", ave, "sum = ", sum)

C++ 檔案

int average(lua_State *L){

    int lua_args_count = lua_gettop(L);

    lua_Number sum = 0;
    for (int i = 0; i < lua_args_count; i++){
        sum += lua_tonumber(L, i);
    }

    lua_pushnumber(L, sum / lua_args_count); // follow order to return value ave
    lua_pushnumber(L, sum); // sum

    // return 2 number to Lua
    return 2;
}

int main(int argc, const char *argv[])
{
    //cout << "lua test platform!!!" << endl;
    string scriptnema = "main.lua";
    string script_char = "print('123')";

    int luaError;
    lua_State *L = luaL_newstate();
    if (L == NULL)
    {
        cout << "luaL_newstate faile !!!" << endl;
        return -1;
    }
    luaL_openlibs(L);
    lua_register(L, "average", average); // "average" --> Lua symbol call C++ function method (local ave, sum = average(11, 20, 63))

    luaError = luaL_dofile(L, scriptnema.c_str());
    lua_close(L);
    system("pause");
    return 0;
}

第31行，這邊主要是讓Lua symbol 可以辨識 average的感覺，還有另一種辦法可以自己創造一個

自己的Lua環境(Lib)，打算在下一篇紀錄下來。

// "average" --> Lua symbol call C++ function method (local ave, sum = average(11, 20, 63))
lua_register(L, "average", average);