Lua

1. While Loop

   Structure:

   while condition do
       put your job here
   end
   

   Example:

   while 1 == 1 do
       print (“I will run forever”)
   end

2. If-else Statement

   Structure:

   if condition then
       job
   end
   

   if x == 0 then
       print (“Why am I nil?”)
   elseif x == 1 then
       print (“Did you flip my bit?”)
   else
       print (“I knew you hate binary. :/ ”)
   end

3. Functions

   Structure:

   function name(variables)
       code(do something)
   end
   

   function sayHello()
       local pocket = true
       print (“Hello Pockets!”)
       if not pockets then
           print (“Who are you?”)
      end
   end

4. Require

   Requiring files in lua is same as using class in Java and Python. When you require some files all the functions as well as variables will be accessible in the current file. Let's have a look.

   $ ls
    time.lua
    main1.lua
    main2.lua
   $

   There are three files in the same directory. Let's see what two of those files have and how to reuse the codes in other files.

   time.lua

   local time = 10
   function printTime()
       print("The current time is : " .. time)
   end
   
   function setTime(t)
       time = t
   end
   
   function getTime(t)
       return time
   end

   Now let's import time.lua in main.lua. There are several ways to import files. Here are few examples. Please feel free to do some googling.

   main1.lua

   require("time.lua")
   print("Main function running...")
   time.printTime()
   time.setTime(20)
   print("The new time is :" .. time.getTime())

   main2.lua

   Fun = require("time.lua")
   print("Main function running...")
   Fun.printTime()
   Fun.setTime(20)
   print("The new time is :" .. Fun.getTime())

   As you can see, both main1.lua and main2.lua will do the same work. The only difference being the way of importing other files. These two ways of requiring files resemble to sort of static and non-static content in Java. If you require by File=require('file1.lua'), you use File to access functions and if you just do require('file1.lua') then you can use file1.functionName() to access functions.

5. Other basics in Lua

   local x = 5
   local x = 3
   if x == y then
       print("X is equal to y")
   end
   
   if x ~= y then
       print("x is not equal to y")
   end
   
   local b = true
   print("b is " .. toString(true)) --This prints 'b is true'
   
   local c = not b
   print("c is " .. toString(true)) --This prints 'c is false'
   
   -- Array --
   
   local arr = {}
   arr[0] = “Hook”
   arr[1] = “Pocket”
   print("I am " .. arr[0]) --This prints: 'I am Hook'
   
   --Length of array
   print("Total length of this array is = " .. toString(#arr)) --Prints: 'Total length of this array is = 2'
   
   local arr1 = {}
   arr1[“robot”] = “Hook”
   arr1[“platform”] = “Nao"
   arr1["company"] = "Aldebaran"
   print("I am " .. arr1["robot"]) --This prints: 'I am Hook'
   print("I am in " .. arr1.platform .. " platform") --This prints: 'I am in Nao platform'
   
   -- Commenting: "--" sign infront of line will make it a comment
      -- This is a comment
   
   -- concatenation (Adding two strings): ".." characters concatenate two strings
   print(“Add me to “ .. var)