Ruby/C2/Variables-in-Ruby/English-timed

Time	Narration
00:02	Welcome to the Spoken Tutorial on Variables in Ruby
00:06	In this tutorial we will learn
00:09	What is a variable?
00:10	Dynamic typing in Ruby
00:13	Declaring a variable
00:15	Converting variable types
00:18	What is variable's scope?
00:20	Types of variables
00:23	Here we are using Ubuntu Linux version 12.04 Ruby 1.9.3
00:32	To follow this tutorial you must have the knowledge of using Terminal in Linux.
00:38	You must also be familiar with irb
00:41	If not, for relevant tutorials, please visit our website
00:47	Now I will explain what a variable is.
00:50	Variable is used to store a value.
00:54	Variable is a reference that can be assigned.
00:58	Please note that Ruby variables are case sensitive.
01:04	Variable names should be meaningful.
01:07	Variable name may only contain lowercase letters, numbers, underscores. Ex : first_name
01:20	Now let us see what is dynamic typing
01:23	Ruby is a dynamic typed language.
01:27	It means that you don't need to declare datatype while creating a variable.
01:34	Ruby interpreter determines the data type at the time of assignment.
01:39	Now let us see how to declare a variable in Ruby.
01:45	Open the terminal by pressing Ctrl, Alt and T keys simultaneously.
01:51	A terminal window appears on your screen.
01:55	Now, type irb
01:57	Press Enter to launch Interactive Ruby
02:02	Now type var1 equal to 10 and Press Enter
02:09	Here we have declared a variable var1 and assigned a value 10 to it.
02:15	Let's check whether the datatype allotted by the interpreter is integer or not.
02:21	So, type var1 dot kind_(underscore)of (?)question mark Integer and press Enter
02:37	We will get the output as true.
02:39	In Ruby you can dynamically change the variable type.
02:44	To do so, just assign a new value to it.
02:47	Let's do this by assigning a string value to variable var1.
02:53	Type var1 equal to within double quote helloand press Enter
03:02	Let's verify the variable type assigned
03:06	Type var1 dot class
03:12	Class method tells us what class of variable it is. Now Press Enter
03:20	We get the output as string
03:23	Ruby has automatically changed the variable type from integer to string
03:29	We will now learn how to convert a variable value to different type
03:35	Lets switch back to slides
03:38	Ruby variable classes have methods to convert their value to a different type
03:45	to_i method is used to convert a variable to integer
03:51	to_f method is used to convert a variable to floating point value
03:57	to_s method is used to convert a variable to string
04:03	to _s method takes number base as an argument.
04:08	The conversion depends on this number base.
04:12	Now let us try out these methods.
04:15	Go to the terminal Lets clear the terminal first
04:21	Press Ctrl L to clear the irb console
04:25	Now Type y equal to 20 and Press Enter
04:32	Here we have declared a variable called y and assigned a value 20 to it.
04:39	We will now convert y to a floating point value using to underscore f method
04:47	Type y dot to underscore f and Press Enter
04:55	We will get the value as float.
04:57	Now Type y dot to underscore s and Press Enter
05:06	We will get output 20 within double quotes
05:10	To convert variable y in binary form give number base as 2 in to_s method
05:18	Press up arrow key to get the previous command
05:22	Type opening bracket 2 closing bracket and press Enter
05:29	We get the output in the binary form
05:33	Similarly you can convert variable y to octal or hexadecimal form
05:39	By changing the number base to 8 or 16.
05:44	Let us switch back to our slide
05:47	We will now learn what is a variable scope.
05:51	Scope defines where in a program a variable is accessible.
05:56	Ruby has four types of variable scope:
06:00	Local
06:01	Global
06:02	Instance and
06:04	Class
06:06	Each variable type is declared by using a special character at the beginning of the variable name
06:14	$ represents global variable
06:18	Lower case letters and underscore represents a local variable
06:25	@ represents an instance variable
06:29	Two @@ symbols represents a class variable
06:33	Upper case letters represents a constant
06:37	We will learn in detail about this in another tutorial.
06:42	This brings us to the end of this Spoken Tutorial. Let us summarises
06:48	In this tutorial we have learnt
06:51	To declare a variable eg var1=10
06:56	Changing variable type using to_f, to_s methods
07:04	Different Variable scope
07:06	As an assignment
07:08	Declare a variable and convert it to octal and hexadecimal form
07:14	Watch the video available at the following link.
07:17	It summarises the Spoken Tutorial project.
07:20	If you do not have good bandwidth, you can download and watch it.
07:24	The Spoken Tutorial Project Team :
07:27	Conducts workshops using spoken tutorials
07:30	Gives certificates to those who pass an online test
07:34	For more details, please write to contact at spoken hyphen tutorial dot org
07:41	Spoken Tutorial Project is a part of the Talk to a Teacher project.
07:45	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
07:51	More information on this Mission is available at the below link
07:57	This is Afrin Pinjari from IIT Bombay, signing off. Thank you for watching.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha