lua通過一個運(yùn)行時棧來維護(hù)參數(shù)傳遞及返回，使用lua_to*等函數(shù)獲取lua傳遞到C函數(shù)的參數(shù)，使用lua_push*從C函數(shù)返回值到lua腳本。此外也可以使用lua_getglobal從C函數(shù)獲取lua腳本定義的全局變量。具體參看例子(
test_lua.c)：
- #include <lua.h>
- #include <lauxlib.h>
- #include <stdlib.h> /* For function exit() */
- #include <stdio.h> /* For input/output */
- void bail(lua_State *L, char *msg){
- fprintf(stderr, "\nFATAL ERROR:\n %s: %s\n\n",
- msg, lua_tostring(L, -1));
- exit(1);
- }
- int lua_func_from_c(lua_State *L)
- {
- printf("This is C\n");
- int argc = lua_gettop(L); /* number of arguments */
- const char * str = lua_tostring(L,1); /* the first argument: string */
- int num = lua_tonumber(L,2); /* the second argument: number */
-
- printf("The first argument: %s\n", str);
- printf("The second argument: %d\n", num);
- lua_getglobal(L,"global_var");
- const char * global_str = lua_tostring(L,-1);
- printf("global_var is %s\n", global_str);
- int the_second_ret = 2*num;
- lua_pushstring(L, "the first return");
- lua_pushnumber(L, the_second_ret);
- return 2; /* tell lua how many variables are returned */
- }
- int main(int argc, const char *argv[])
- {
- if(argc != 2)
- {
- return 1;
- }
- lua_State *L = luaL_newstate(); /* Create new lua state variable */
- /* Load Lua libraries, otherwise, the lua function in *.lua will be nil */
- luaL_openlibs(L);
-
- /* register new lua function in C */
- lua_register(L, "lua_func_from_c", lua_func_from_c);
- if( luaL_loadfile(L,argv[1]) ) /* Only load the lua script file */
- bail(L, "luaL_loadfile() failed");
- if( lua_pcall(L,0,0,0) ) /* Run the loaded lua file */
- bail(L, "lua_pcall() failed");
- lua_close(L); /* Close the lua state variable */
- return 0;
- }
lua腳本（my.lua）如下所示(在lua腳本中，如果變量不用local明確聲明為局部變量，則默認(rèn)為全局變量)：
- print("Hello world")
- global_var = "this is a global string"
- first, second = lua_func_from_c("the first one", 2)
- print("the first returned", first)
- print("the second returned", second)
執(zhí)行結(jié)果：
$ ./a.out my.lua
Hello world
This is C
The first argument: the first one
The second argument: 2
global_var is this is a global string
the first returned the first return
the second returned 4
