Ruby/C3/for-and-each-Looping-Statements/English-timed

Time	Narration
00:01	Welcome to the tutorial on for and each Loops in Ruby.
00:05	In this tutorial, we will learn:
00:07	Meaning of the term “loop” . The different kinds of loops in Ruby
00:11	Usage of “for” loop and Usage of “each” looping construct.
00:14	Here, we are using:
00:16	Ubuntu version 12.04
00:19	Ruby 1.9.3
00:22	To follow this tutorial, you must have Internet connection.
00:25	You must also have knowledge of Linux commands, Terminal and Text-editor.
00:30	If not, for relevant tutorials, please visit our website.
00:34	Now, let me explain what is referred to as a “loop” in Ruby.
00:38	A loop is a command or set of commands that are executed a fixed number of times.
00:44	Ruby has the following main looping statements.
00:47	for, each
00:49	while, until.
00:50	In this tutorial, we will learn how to use the for and each looping constructs.
00:55	Before we begin, please create the following folders in your home directory-
01:02	ttt, ruby hyphen tutorial, looping hyphen statements.
01:07	Please create the sub-folders as mentioned there.
01:11	Now we have created the requisite folders.
01:13	Let's move ahead.
01:15	The syntax of the “for” loop in Ruby is as follows:
01:19	for “variable” in “a collection of objects”
01:22	ruby code end
01:25	Let us try to understand it with an example.
01:28	Create a new file in gedit as shown in the basic level Ruby tutorials
01:32	and name it for hyphen loop dot rb .
01:36	I already have a working example of the “for” loop.
01:39	You can type the code as we go through this example.
01:44	I have declared a “for” loop in this example.
01:47	We have a set of numbers 1 to 20.
01:50	We declare a variable called “i” within the “for” loop.
01:55	The variable “i” gets initialized to the first element in the set of numbers 1 to 20.
02:00	The “for” loop declaration causes the code to iterate over each element in the set 1 to 20.
02:07	The “puts” method declared within the “for” loop is responsible for generating the output.
02:14	Now, open the terminal and type:
02:17	ruby space for hyphen loop dot rb and see the output.
02:22	The output will be an array of numbers 1 to 20.
02:26	In this example, we declared a “for” loop for an inclusive range.
02:31	It included all numbers from 1 to 20.
02:35	Next, we shall look at implementing the “for” loop for a non-inclusive range.
02:41	Continue to type the next part of the code.
02:44	Non-inclusive means it will not include the last element in the collection of objects.
02:49	Here, “for” loop is implemented for a non-inclusive range of numbers 1 to 20.
02:55	You will notice shortly that the number 20 will not be printed in the output.
02:59	The last number does not get included when you have 3 dots between numbers.
03:04	Now, open the terminal and type: ruby space for hyphen loop dot rb
03:13	and see the output.
03:17	The output will still be an array of numbers but will not include the number 20.
03:22	Now, you should be capable enough to write your own “for” loop.
03:27	The syntax of the “each” loop in Ruby is as follows:
03:31	“a collection of objects” dot each, do item
03:36	ruby code end
03:38	Let us try to understand it with an example.
03:42	Create a new file in gedit as shown in the basic level Ruby tutorials
03:46	and name it each hyphen loop dot rb.
03:50	I already have a working example of the each loop.
03:53	You can type the code as we go through this example.
03:58	I have declared an each loop in this example.
04:03	We have a set of numbers 1 to 20.
04:06	We declare a variable called “i” within the each loop.
04:11	The “i” variable gets initialized to the first element in the set of numbers 1 to 20.
04:17	The each loop declaration causes the code to iterate over each element in the set 1 to 20.
04:23	The puts method declared, within the each loop, is responsible for generating the output.
04:30	Now, open the terminal and type: ruby space each hyphen loop dot rb
04:39	and see the output.
04:43	The output will be an array of numbers 1 to 20.
04:46	In the above example, we declared an each loop for an inclusive range.
04:51	It included all numbers from 1 to 20.
04:54	Next we shall look at implementing the each loop for a non-inclusive range.
05:00	Continue to type this part of the code.
05:04	Non-inclusive means it will not include the last element in the collection of objects.
05:10	Here, an each loop is implemented for a non-inclusive range of numbers 1 to 20.
05:16	You will notice shortly that the number 20 will not be printed in the output.
05:20	The last number does not get included when you have 3 dots between numbers.
05:25	Now, open the terminal and type: ruby space each hyphen loop dot rb
05:34	and see the output.
05:39	Now you should be capable enough to write your own each loop.
05:44	How would we determine which looping construct to choose?
05:48	Let us try to recall the "for" loop construct.
05:53	In the first example, we iterated over a set of numbers from 1 to 20 using for loop.
05:59	Execute: ruby space for hyphen loop dot rb in your terminal, see the output.
06:08	Now, look at the code in gedit.
06:11	When you invoke the for loop, Ruby is actually calling the each method behind the scenes.
06:16	And, calling each or for will generate the same output.
06:21	Since the call to for in turn calls each, it is preferable to use the each loop instead.
06:28	This brings us to the end of this Spoken Tutorial.
06:30	Let's summarize.
06:32	In this tutorial, we have learnt: Usage of for loop
06:35	Usage of each construct
06:38	Reasoning behind using each instead of for
06:41	Examples of using the above looping constructs.
06:45	As an assignment-
06:47	Write a ruby program using the appropriate loop construct
06:50	to create an output of even numbers from a set of numbers, say 1 to 20.
06:56	Watch the video available at the following link.
07:00	It summarizes the Spoken Tutorial project.
07:03	If you do not have good bandwidth, you can download and watch it.
07:08	The Spoken Tutorial project team:
07:11	Conducts workshops using spoken tutorials.
07:14	Gives certificates to those who pass an online test.
07:18	For more details, please write to: contact@spoken-tutorial.org
07:23	Spoken Tutorial project is a part of the Talk to a Teacher project.
07:26	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
07:33	More information on this mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
07:41	This is Anjana Nair, signing off. Thank you.

Contributors and Content Editors

Jyotisolanki, PoojaMoolya, Pratik kamble, Sandhya.np14