[practice] Lua interact with C

main.c

#include "lua.h"
#include "lauxlib.h"

#include<stdio.h>
#include<stdlib.h>

int l_bar0(lua_State *L){
    printf("----------- in the bar0 ---------------\n");
    printf("----------- out the bar0 ---------------\n\n");
    return 0;
}

int l_bar1_int(lua_State *L){
    printf("----------- in the bar1 ---------------\n");
    printf("gettop : %d\n",lua_gettop(L));
    int input_from_lua = lua_tointeger(L,-1);
    printf("input is %d\n",input_from_lua);
    lua_pop(L,1);
    printf("gettop : %d\n",lua_gettop(L));
    printf("----------- out the bar1 ---------------\n\n");
    return 0;
}

int l_bar1_str(lua_State *L){
    printf("----------- in the bar1_str ---------------\n");
    printf("gettop : %d\n",lua_gettop(L));
    char* input_from_lua = lua_tostring(L,-1);
    printf("input is %s\n",input_from_lua);
    printf("gettop : %d\n",lua_gettop(L));
    lua_pop(L,1);
    printf("----------- out the bar1_str ---------------\n\n");
    return 0;
}

int l_bar2(lua_State *L){
    printf("----------- in the bar2 ---------------\n");
    printf("gettop : %d\n",lua_gettop(L));
    char* input_from_lua = lua_tostring(L,-1);
    lua_pop(L,1);
    int input_int = lua_tonumber(L,-1);
    lua_pop(L,1);
    sprintf(input_from_lua,"%s - %d",input_from_lua,input_int);
    printf("result is %s\n",input_from_lua);
    printf("gettop : %d\n",lua_gettop(L));
    printf("----------- out the bar2 ---------------\n\n");
    return 0;
}

int main(int argc, char *argv[]){

    // new a lua VM
    lua_State *L = luaL_newstate();

    // open all libraries
    luaL_openlibs(L);

    lua_register(L,"bar0",l_bar0);
    lua_register(L,"bar1",l_bar1_int);
    lua_register(L,"bar1_str",l_bar1_str);
    lua_register(L,"bar2",l_bar2);

    // do file
    luaL_dofile(L,"test.lua");

    // call foo
    lua_getglobal(L,"foo");
    lua_pushnumber(L,19);
    lua_pcall(L,1,1,0);
    // show res
    double res = lua_tonumber(L,-1);
    lua_pop(L,1);
    printf("result = %f\n", res);

    // call hello
    lua_getglobal(L,"hello");
    lua_pushstring(L,"Me");
    lua_pcall(L,1,0,0);

    // call charAt
    int input_int = 0;
    printf("Need index of \"Hello World\" : ");
    scanf("%d",&input_int);
    lua_getglobal(L,"charAt");
    lua_pushinteger(L,input_int);
    lua_pushstring(L,"Hello World");
    lua_pcall(L,2,1,0);
    char *ch = lua_tostring(L,-1);
    // show result
    if(ch){
        printf("%d of \"Hello World\" is %s\n",input_int, ch);
    }else{
        printf("Happend error!!\n");
    }
    lua_pop(L,1);

    // get t1.a
    lua_getglobal (L,"t1");
    lua_pushstring(L,"a");
    lua_gettable  (L,-2);
    int t_v = lua_tointeger(L,-1);
    lua_pop(L,1);
    printf("t1.a = %d\n", t_v);
    // get t1.b
    lua_getglobal (L,"t1");
    lua_pushstring(L,"b");
    lua_gettable  (L,-2);
    int t_vb = lua_tointeger(L,-1);
    lua_pop(L,1);
    printf("t1.b = %d\n", t_vb);
    lua_pop(L,1);

    //call showTable
    lua_getglobal (L,"showTable");
    lua_newtable  (L);
    lua_pushstring(L,"key1");
    lua_pushstring(L,"value1");
    lua_settable  (L,-3);
    lua_pushstring(L,"key2");
    lua_pushstring(L,"value2");
    lua_settable  (L,-3);
    lua_pushstring(L,"key3");
    lua_pushstring(L,"value3");
    lua_settable(L,-3);
    lua_pcall(L,1,0,0);
    lua_pop(L,1);    // pop table

    printf("getstatic : %d\n",lua_getstack(L,0,NULL));
    printf("gettop : %d\n",lua_gettop(L));



    printf("-------------------------------\n");

    return 0;
}

makefile

all:
	gcc main.c -o main -I/usr/include/lua5.3/ -L/usr/lib/x86_64-linux-gnu/ -llua5.3
clean:
	rm main

test.lua

var = 1000
t1  = {
   a = 100,
   b = 2,
}

function foo(y)
   print "................... in function foo  ..............."
   print "................... out function foo ..............."
   print ()
   return y * y
end

function hello(name)
   print "................... in function hello  ..............."
   print ("Hello " .. name)
   print "................... out function hello ..............."
   print ()
end


function charAt(index,str)
   print "................... in function charAt  ..............."
   print ("result is "..str:sub(index,index+1))
   print "................... out function charAt ..............."
   print ()
   return str:sub(index,index)
end

function showTable(t)
   print "................... in function showTable  ..............."
   for k,v in pairs(t) do
      print(k .. "-----" .. v) 
   end
   print "................... out function showTable ..............."
   print ()
end



bar0()

bar1(12354)

bar1_str("Lua")

bar2(var,"Hello World in Lua")