Deep LUA stack interaction-cpp calling LUA data

LUA interacts with C by lua_state this stack.

1.....lua stack index upward growth such as: 1 2 3 4 5 62.....lua Stack index is the following index to the bottom is 3 2 1 0-1-2-3, the stack corresponds to a value of 1 2 3 x 1 2 3 3......lua functions multiple return values if the function above returns 3 return values, then return a, B,c a=3 b=2 c=1 first return value first into the stack

Stack pop problem: Lua_pop (x), X is the number of POPs, general call function after pop (1) because the general return value only one

PS: When calling a function, there is no stack balance, the return is balanced, and the value requires a stack cleanup for the returned value.

Examples of data in C + + using LUA

extern  "C" {#include   "src/lualib.h" #include   "src/lauxlib.h" #include   "src/lua.h"} #include   "iostream" Using namespace std;lua_state*l;int get_sum (int x, int y) {int  sum=0;lua_getglobal (l,  "get_sum");/* Call Function */lua_pushnumber (l, x); Lua_pushnumber (l, y);  lua_call (l, 2, 3);/* Parameter 2, return value 3 x */cout <<  "top is  "  < < lua_gettop (L)  << endl;cout << lua_tonumber (L, lua_gettop (L)  - 0)  << endl;cout << lua_tonumber (L, lua_gettop (L)  -  1)  << endl;cout << lua_tonumber (L, lua_gettop (l)  - 2)  << endl;cout << lua_tonumber (L, lua_gettop (L)  - 2)  < < endl;cout << lua_tonumber (L, lua_gettop (L)  - 3)  <<  Endl;cout << lua_tonumber(L, lua_gettop (L)  - 4)  << endl;cout << lua_tonumber (L, lua _gettop (L)  - 5)  << endl;cout << lua_tonumber (L, lua_gettop (L)  - 6)  << endl;cout << lua_tonumber (L, lua_gettop (L)  -  7)  << endl;cout << lua_tonumber (L, lua_gettop (l)  - 8)  << endl;cout << lua_tonumber (L, lua_gettop (L)  - 9)  < < endl;lua_pop (l, 3);/*function returned 3 values */cout <<  "\ n"  << endl;lua _getglobal (l,  "B");/* Get variable   Press in stack */cout << "b="  <<lua_tonumber (L, lua_gettop ( L)/*1*/ )  << endl;lua_getglobal (l,  "a");/* Get variable   Press in stack */cout <<  "a = " << lua_tonumber (l, lua_gettop (L)/*1*/)  << endl;lua_getglobal (l, ") C ");/* Get variable   press in stack */cout <<  "c="  << lua_tonumber (L, lua_gettop (L)/*1*/)  <<  Endl;lua_pop (l, 3);/* Clear Stack */cout <<  "Top is"  << lua_gettop (l)   << endl;return sum;} Int main () {l = lua_open (); Lual_openlibs (L); Lual_dofile (l,  "A.lua");//cout <<  get_sum (1, 2)  << endl;get_sum (1, 2); Lua_close (l); system ("pause"); return 0 ;}

a=10;

b=11;

c=12;

function Get_sum (arg_1,arg_2)

Return arg_1+arg_2, "100", "200";

End

Deep LUA stack interaction-cpp calling LUA data