Difference between revisions of "Ruby/C2/Control-Statements/English-timed"

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|* Conducts workshops using spoken tutorials.  
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|* Gives certificates to those who pass an online test.  
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|For more details, please write to:
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|For more details, please write to: contact@spoken-tutorial.org
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contact@spoken-tutorial.org
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| '''Spoken Tutorial''' project is a part of the '''Talk to a Teacher''' project.
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|More information on this mission is available at:
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|More information on this mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
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spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
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Latest revision as of 12:19, 10 March 2017

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 , 'elsif' statement
00:11 'else, 'case' statements.
00:14 Here we are using: 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. 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 if 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” , ruby code
02:20 else, 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.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 . 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 declared a local variable my_num and assigned 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 If 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 Let's 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 . when “value 2” ruby code
06:31 else ruby code . 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 a 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 the 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. In this tutorial, we have learnt to use:
09:10 if statement
09:12 else construct, if-elsif and
09:15 case statements.
09:17 As an assignment- 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 is 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 multiple of 2, 3 or 4”.
09:56 Watch the video available at the following link.
10:00 It summarizes 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

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