gistfile1.txt

#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>

#include <stdio.h>

void maFonctionC(){
    printf("Cool\n");
}

int main(int argc, char** argv, char** env){

	lua_State *L = lua_open();
	luaL_openlibs(L);
        luaL_dofile(L, "script.lua");

        static const luaL_reg cfunc[]={
		{"func", maFonctionC},
		{NULL, NULL}
	};
        luaL_register(L, "c", renderfunc);

        char buff[256];
        int error;

        while (1){
        	lua_getfield(L, LUA_GLOBALSINDEX, "update");
	        lua_call(L, 0, 0);
        }

	return 0;
}

script.lua

function update()
    c.maFonctionC()
end