Lua C API Tutorial

Getting Set Up

If you don't already have the Lua development libraries installed, head on over to the Lua download page to grab the latest version. There are installation instructions included, but they can also be found here.

Setting Up the Lua State

Now that you have Lua installed, you can include the development headers in your C project by adding the following lines near the top:

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#include <lua5.2/lua.h>

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#include <lua5.2/lualib.h>

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#include <lua5.2/lauxlib.h>

Great, Lua is now included in your project. You can call any of the functions provided. Lets go ahead and set up the Lua state.

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// Create a new Lua state

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lua_State *L = luaL_newstate();

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// Initialize all default Lua libraries

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luaL_openlibs(L);

Firstly, we create the new Lua state by calling luaL_newstate() Next, we initialize all of the default Lua libraries by calling luaL_openlibs(L) Now that the Lua state is open, you may call functions like lua_getglobal and lua_pushstring

Running Your Lua Script

We have the Lua state open and running, but it has no code to execute. In order to load a script, we use the code:

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// Load the script
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if (luaL_loadfile(L, "player.lua") != LUA_OK) {

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  printf("lua: %s\n", lua_tostring(L, -1));

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}

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// Execute the script

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if (lua_pcall(L, 0, 0, 0)) {

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  printf("lua %s\n", lua_tostring(L, -1));

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}

Congradulations, the script player.lua has now run. If there were any errors, they would've been printed to stdout. Now that the script has run, we can call the following to cleanup the Lua state.

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// Close the Lua state

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lua_close(L);

Compiling

When compiling a C project with the Lua API, we have to link against the Lua development library. The following command will compile our sample program with Lua.

gcc embeddinglua.c -llua

If you wish to download the full source for this tutorial, it can be found here.

Finished

Hooray! If you followed this tutorial correctly, you now have a functioning Lua state and can control your Lua scripts! Sample Lua script