So you want to use Lua to script your C program?
Here's a basic C code skeleton (hosting the Lua runtime) that allows you to run
a Lua script via host lua_script.lua with the Lua script able to directly call
the say_something function defined in the C host program.
Assuming you have a C/C++ compiler such as the DevKit installed on your Windows box as well as the Lua headers and library, build the executable using something like:
C:\>gcc -Wall -O3 -s -o host.exe -Ic:/lua/include -Lc:/lua/bin -llua51 host.c C:\>
More details and examples in future posts.
/* file: host.c */
#include <stdio.h>
#include <stdlib.h>
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
/* Variable arg function callable from a Lua script as:
* say_something('A', 'gaggle', 'of', 5, 'args')
*/
static int
say_something(lua_State* luaVM) {
int n = lua_gettop(luaVM);
int i;
if (n == 0) {
printf("no arguments");
return 0;
}
for (i = 1; i <= n; i++) {
if (!lua_isstring(luaVM, i)) {
lua_pushstring(luaVM, "[ERROR] argument must be a string or a number");
lua_error(luaVM);
}
printf("%s\n", lua_tostring(luaVM, i));
}
return 0;
}
static void
print_usage(void) {
fprintf(stderr, "usage: %s lua_script\n", "main");
fflush(stderr);
}
static int
check_args(int arg_count, char** arg_strings) {
if (arg_count != 2) {
print_usage();
return(0);
} else {
return(1);
}
}
static void
err_message(const char* msg) {
fprintf(stderr, "%s\n", msg);
fflush(stderr);
}
int
main(int argc, char** argv) {
if (!check_args(argc, argv)) return(EXIT_FAILURE);
/* Initialize Lua */
lua_State* luaVM = luaL_newstate();
if (luaVM == NULL) {
err_message("Cannot initialize Lua; exiting...");
return EXIT_FAILURE;
}
/* Stop the GC during Lua library (all std) initialization and function
* registrations. C functions that are callable from a Lua script must be
* registered with Lua.
*/
lua_gc(luaVM, LUA_GCSTOP, 0);
luaL_openlibs(luaVM);
lua_register(luaVM, "say_something", say_something);
lua_gc(luaVM, LUA_GCRESTART, 0);
/* Execute the Lua script */
if (luaL_dofile(luaVM, argv[1])) err_message("Problem running script.");
/* Lua cleanup */
lua_close(luaVM);
return EXIT_SUCCESS;
}