1 – Getting Started
To keep with the tradition, our first program in Lua just prints «Hello World» :
If you are using the stand-alone Lua interpreter, all you have to do to run your first program is to call the interpreter (usually named lua ) with the name of the text file that contains your program. For instance, if you write the above program in a file hello.lua , the following command should run it:
As a slightly more complex example, the following program defines a function to compute the factorial of a given number, asks the user for a number, and prints its factorial:
-- defines a factorial function function fact (n) if n == 0 then return 1 else return n * fact(n-1) end end print("enter a number:") a = io.read("*number") -- read a number print(fact(a)) If you are using Lua embedded in an application, such as CGILua or IUPLua, you may need to refer to the application manual (or to a «local guru») to learn how to run your programs. Nevertheless, Lua is still the same language; most things that we will see here are valid regardless of how you are using Lua. For a start, we recommend that you use the stand-alone interpreter (that is, the lua executable) to run your first examples and experiments.
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