(Lua) C++ 呼叫 Lua 的變數、函式

簡單的在C++裡頭與Lua交互操作

首先提供 Lua 的簡單範例

 print(" Lua 2019/01/07 !!!")

 -- Variable
 monster_type = "Ghost"
 blood = 99.9

 -- Table
 x_table = {, , }

 -- Function
 function f(var)
     return var * var +  * var +
 end

呼叫變數的辦法

 int main(int argc, const char *argv[])
 {
     string scriptnema = "main.lua";
     int luaError;
     lua_State *L = luaL_newstate();

     if (L == NULL)
     {
         cout << "luaL_newstate faile !!!" << endl;
         return -;
     }

     luaL_openlibs(L);
     // first getbloable parameter that it will be first on the stack.
     // stack index number will follow small to large [1 ... 5] or [-5 ... -1]
     lua_getglobal(L, "blood");
     lua_getglobal(L, "monster_type"); 

     double blood = lua_tonumber(L, ); // index = 1 or -2
     string type = lua_tostring(L, );  // index = -1 or 2

     cout << "blood = " << blood << endl;
     cout << "monster_typa = " << type.c_str() << endl;

 }

呼教 table的方式

 int main(int argc, const char *argv[])
 {
     //cout << "lua test platform!!!" << endl;
     string scriptnema = "main.lua";
     int luaError;
     lua_State *L = luaL_newstate();

     if (L == NULL)
     {
         cout << "luaL_newstate faile !!!" << endl;
         return -;
     }

     luaL_openlibs(L);
     luaL_dofile(L, scriptnema.c_str());

     lua_getglobal(L, "x_table");
     lua_Integer array_len = luaL_len(L, -);
     cout << "array_len = " << array_len << endl;

     for (int i = ; i > ; i--){
         lua_rawgeti(L, -, i); // lua_rawgeti(lua stack, index, value)
         cout << lua_tonumber(L, -) << endl;
         lua_pop(L, );
     }
 }

在 C++ 輸入變數給 Lua 且 return 結果

 int luaf(lua_State *L){
     double sum;
     lua_getglobal(L, "f");

     lua_pushnumber(L, );

     lua_call(L, , ); // lua_call(lua stack, input num, output num)

     sum = (int)lua_tonumber(L, );

     lua_pop(L, );

     return sum;
 }

 int main(int argc, const char *argv[])
 {
     //cout << "lua test platform!!!" << endl;
     string scriptnema = "main.lua";
     int luaError;
     lua_State *L = luaL_newstate();

     if (L == NULL)
     {
         cout << "luaL_newstate faile !!!" << endl;
         return -;
     }

     luaL_openlibs(L);
     luaL_dofile(L, scriptnema.c_str());

     cout << luaf(L) << endl;
     lua_close(L);
     system("pause");
 }

以上是 Lua --> Stack 基本API應用，希望最後是把所有的API都玩過一遍。

這樣之後學習與應用時可以更加靈活