Ruby/C2/Control-Statements/English-timed

Time'	Narration
00.01	Welcome to the spoken tutorial on Control Statements in Ruby.
00.06	In this tutorial we will learn to use
00.08	if statement
00.09	elsif statement
00.11	else
00.12	case statements
00.14	Here we are using
00.15	Ubuntu version 12.04
00.18	Ruby 1.9.3
00.21	To follow this tutorial, you must have Internet Connection.
00.24	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	Before we begin, recall that we had created “ttt” directory earlier.
00.38	Let's go to that directory.
00.41	Then to ruby hyphen tutorial control hyphen statements
00.47	Now that we are in that folder, let’s move ahead.
00.52	The syntax of the if statement in Ruby is as follows:
00.56	if “condition”
00.58	ruby code
00.59	end
01.01	Let us look at an example.
01.03	Create a new file in gedit as shown in the basic level Ruby tutorials.
01.08	Name it if hyphen statement dot rb
01.12	I have a working example of the if statement.
01.15	You can pause the tutorial, and type the code as we go through it.
01.19	I have declared an if statement in this example.
01.23	First, I declare a local variable my_num and assign the value 2345 to it.
01.31	Then I declare an if statement.
01.34	The puts method declared within the if statement will display the output.
01.39	The if statement will check the value of my_num is greater than 0.
01.43	If it is, it will print out the specified string.
01.47	Now, let us switch to the terminal and type
01.51	ruby space if hyphen statement dot rb
01.57	The output will display “The value of my_num is greater than 0”.
02.02	This output proves that the if condition returned true.
02.07	You should now be able to write your own if statement in Ruby.
02.12	Let's look at the if-else statement next.
02.16	The syntax for using else is:
02.18	if “condition”
02.19	ruby code
02.20	else
02.21	ruby code
02.22	end
02.24	Let us look at an example.
02.26	Create a new file in gedit as shown in the basic level Ruby tutorials.
02.30	Name it if hyphen else hyphen statement dot rb
02.37	I have a working example of the if-else statement.
02.40	You can pause the tutorial, and type the code as we go through it.
02.44	I have declared an if-else statement in this example.
02.48	First I declare a local variable my_num and assign the value of -1 to it.
02.55	Then I declare an if statement.
02.58	The if statement will check if the value of my_num is greater than 0.
03.03	If it is, it will print out the specified string.
03.06	If not, it will go to the else statement.
03.10	And it will print out the string that is specified there.
03.13	Now, let us switch to the terminal and type
03.18	ruby space if hyphen else hyphen statement dot rb
03.26	and see the output.
03.27	The output will display “The value of my_num is lesser than 0”.
03.32	This shows that the else statement was executed.
03.35	You should now be able to write your own if-else statement in Ruby.
03.41	Let's look at the if-elsif statement next.
03.45	The syntax for using elsif is:
03.48	if “condition” ruby code
03.50	elsif “condition” ruby code
03.52	else ruby code
03.54	end
03.55	Let us look at an example.
03.58	Create a new file in gedit as shown in the basic level Ruby tutorials.
04.01	Name it if hyphen elsif hyphen statement dot rb
04.07	I have a working example of the if-elsif- statement.
04.10	You can pause the tutorial, and type the code as we go through it.
04.14	I have declared an if-elsif statement in this example.
04.19	Here also, I have declare a local variable my_num and assign the value -1 to it.
04.25	Then I declare an if statement.
04.28	The if statement will check if the value of my_num is greater than 0.
04.32	If it is, it will print out the specified string.
04.35	If this is not true , it will go into the elsif section.
04.39	It will now check if the value of my_num is equal to -1.
04.43	If it is true, it will print out the string that is specified there.
04.46	The value of my_num is neither greater than 0 nor equal to -1 it will go into the else section.
04.54	But since the value of my_num = -1 it will not proceed to the else block.
05.00	And it will exit the conditional statement.
05.03	Now, let us switch to the terminal and type
05.07	ruby space if hyphen elsif hyphen statement dot rb
05.15	and see the output.
05.17	The output will display “The value of my_num is -1 and is lesser than 0”.
05.23	Let's go back to our file and change the value of my_num to 5.
05.29	Let's save the code and execute it on the terminal.
05.35	So, now it fulfills the if condition and the specified string is printed.
05.42	The value of my_num is greater than 0
05.45	Let's go back to our file and change the value of my_num to -5
05.50	Lets save the code and execute it on the terminal
05.55	In this case it fulfills the else condition and the puts statement within the else block gets executed.
06.03	You should now be able to write your own if- elsif statement in Ruby.
06.08	Let us look at the case statement next.
06.12	The case statement is a control flow statement based on a particular selection.
06.17	Let us look at the syntax of the case statement in order to understand this statement.
06.22	The syntax for using case is:
06.24	case variable
06.26	when “value 1”
06.28	ruby code
06.29	when “value 2”
06.30	ruby code
06.31	else
06.32	ruby code
06.34	end
06.35	Let us look at an example.
06.37	Create a new file in gedit as shown in the basic level Ruby tutorials.
06.41	Name it case hyphen statement dot rb
06.44	I have a working example of the case statement.
06.48	You can pause the tutorial, and type the code as we go through it.
06.52	I have declared an case statement in this example.
06.55	Here I have a print statement, which will print a question on the terminal.
07.01	Then I call a gets, which will accept a single line of data from the standard input.
07.09	Then I strip the input data of any new line characters using chomp.
07.15	I assign the result to a variable named domain.
07.18	Then I declare a case statement.
07.22	Within that I declare a when statement .
07.25	This checks whether the specified string matches value of domain.
07.30	First it checks whether the value of domain is “UP”.
07.34	If it is so, it will print out “Uttar Pradesh” and exit the case statement.
07.39	If domain is not “UP”, it checks whether the value of domain is “MP”.
07.44	If it is so, it will print out “Madhya Pradesh” and so on.
07.48	It will continue checking the value of domain if no match was found so far.
07.53	At this point it will encounter the else statement
07.56	as none of the above conditions were true.
07.59	It will subsequently execute the ruby code that follows the else declaration.
08.03	It will print “Unknown” as per our example.
08.07	Now, save the file, switch to the terminal and type
08.11	ruby space case hyphen statement dot rb.
08.18	“Enter the state you live in:” will be displayed on the terminal.
08.22	Type in “UP” and see the output.
08.25	The output will display “Uttar Pradesh”.
08.28	Next execute the Ruby file again, like before.
08.31	This time at the prompt type “KL” and see the output.
08.36	It will print “Kerala”.
08.38	Next execute the file one more time.
08.41	This time at the prompt type in “TN” and see the output.
08.47	It will print “Unknown”.
08.50	This is because none of the cases were satisfied. So, the default else statement is executed.
08.58	You should now be able to write your own case-statements in Ruby.
09.03	This brings us to the end of this Spoken Tutorial.
09.07	Let's summarize.
09.08	In this tutorial we have learnt to use
09.10	if statement
09.12	else construct
09.13	if-elsif and
09.15	case statements
09.17	As an assignment :
09.18	Write a Ruby program :
09.20	that prompts a user to enter a number
09.23	then use the appropriate control-statement
09.26	to check if the number is a multiple of 2
09.29	if it is, then print “The number entered is a multiple of 2”
09.35	if not, it should check if it is a multiple of 3
09.38	if it is, then print “The number entered is a multiple of 3”
09.43	if not, it should check if it a multiple of 4
09.47	if it is, then print “The number entered is a multiple of 4”
09.51	if not, it should print “The number is not a multple of 2, 3 or 4”
09.56	Watch the video available at the following link.
10.00	It summarises the Spoken Tutorial project.
10.03	If you do not have good bandwidth, you can download and watch it.
10.07	The Spoken Tutorial Project Team :
10.09	Conducts workshops using spoken tutorials
10.13	Gives certificates to those who pass an online test
10.16	For more details, please write to contact@spoken-tutorial.org
10.21	Spoken Tutorial Project is a part of the Talk to a Teacher project.
10.26	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
10.32	More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro
10.41	This is Anjani Nair signing off. Thanks for watching.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14