Getting started with Lua and C++
================================

Step 1: Install Lua
--------------------------------

    $ sudo apt-get install libreadline5-dev
    $ sudo apt-get install lua-5.1 liblua5.1-0-dev


Step 2: Test C++ and Lua 
------------------------

<pre><code>
/*
moon1.cpp
*/
#include <iostream>

extern "C" {
    #include "lua.h"
    #include "lualib.h"
    #include "lauxlib.h"  
}

void report_errors(lua_State *L, int status)
{
    if ( status!=0 ) {
        std::cerr << "-- " << lua_tostring(L, -1) << std::endl;
        lua_pop(L, 1); // remove error message
    }
}

int main(int argc, char** argv)
{
    for ( int n=1; n<argc; ++n ) {
        const char* file = argv[n];

        lua_State *L = lua_open();
        luaL_openlibs(L);

        std::cerr << "-- Loading file: " << file << std::endl;
        int s = luaL_loadfile(L, file);
        if ( s==0 ) {
            // execute Lua program
            s = lua_pcall(L, 0, LUA_MULTRET, 0);
        }

        report_errors(L, s);
        lua_close(L);
        std::cerr << std::endl;
    }
    return 0;
}
</code></pre>

The above code runs on Lua 5.1. There is an important change in Lua 5.1 API which requires the `luaopen_*` functions to be called through Lua, like Lua functions. See `luaL_openlibs(L);` line. 

Compile

<pre><code>
    $ gcc moon1.cpp -o moon1 `pkg-config --cflags --libs lua5.1`
</code></pre>

Create a simple Lua script 

<pre><code>
-- hello.lua
print ("Hello Lua")
</code></pre>

Run the Lua script via the CPP program.

<pre><code>
$ ./moon1 hello.lua
-- Loading file: hello.lua
Hello Lua
</code></pre>