Difference between revisions of "Ruby/C3/while-and-until-Looping-Statements/English-timed"

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| Welcome to the tutorial on '''while''' and '''until loops''' in Ruby.  
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| Welcome to the tutorial on '''while and until loops''' in '''Ruby'''.  
  
 
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|* ''''while' loop '''
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| ''''while' loop ''',  ''''until' loop '''
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|* ''''until' loop '''
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|* '''redo''' and
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| '''redo''' and '''break'''.   
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|* '''break'''.   
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| We are using:  
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| We are using:  ''' Ubuntu''' version '''12.04'''  
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|* ''' Ubuntu''' version '''12.04'''  
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|* '''Ruby 1.9.3'''
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| '''Ruby 1.9.3'''
  
 
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|''' ruby code ''', '''end'''  
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|'''end'''  
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|'''ruby code '''
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|'''ruby code ''', '''redo'''
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|'''redo'''
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|'''end conditional'''
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|'''end conditional''', '''end''' loop  
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| '''end''' loop  
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|Let's switch to the '''terminal''' and type:
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|Let's switch to the '''terminal''' and type: '''ruby space redo hyphen loop dot rb'''
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'''ruby space redo hyphen loop dot rb'''
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|and see the output.  
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|and see the output. The output will consist of an '''infinite loop''' that never ends.  
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|The output will consist of an '''infinite loop''' that never ends.  
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| '''a conditional statement '''
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| '''a conditional statement ''', '''break '''
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|'''break '''
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|'''ruby code''', '''end loop '''
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|'''end loop '''
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|Now, let us switch to the '''terminal''' and type:
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|Now, let us switch to the '''terminal''' and type: '''gedit space break hyphen loop dot rb space ampersand.'''
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'''gedit space break hyphen loop dot rb space ampersand.'''
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|* '''while''' loop  
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|'''while''' loop,  '''until''' construct  
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|* '''until''' construct  
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|* '''redo'''
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| '''redo''',  '''break''' construct.  
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|* '''break''' construct.  
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|* Conducts workshops using spoken tutorials.  
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| Conducts workshops using spoken tutorials.  
  
 
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|08:15
 
|08:15
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|* Gives certificates to those who pass an online test.  
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|Gives certificates to those who pass an online test.  
  
 
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| 08:19
 
| 08:19
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|For more details, please write to contact@spoken-tutorial.org
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|For more details, please write to: '''contact@spoken-tutorial.org'''
  
 
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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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|More information on this mission is available at: '''spoken hyphen tutorial dot org slash NMEICT hyphen Intro'''.
  
 
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|-

Latest revision as of 12:34, 10 March 2017


Time Narration
00:01 Welcome to the tutorial on while and until loops in Ruby.
00:06 In this tutorial, we will learn to use-
00:09 'while' loop , 'until' loop
00:11 redo and break.
00:13 We are using: Ubuntu version 12.04
00:17 Ruby 1.9.3
00:20 To follow this tutorial, you must have Internet connection.
00:25 You must also have knowledge of Linux commands, Terminal and Text-editor.
00:29 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 and looping hyphen statements directories.
00:46 Now that we are in that folder, let’s move ahead.
00:50 The syntax of the while loop in Ruby is as follows:
00:54 while “boolean expression”
00:56 ruby code , end
00:58 Let us look at an example.
01:01 Create a new file in gedit as shown in the basic level Ruby tutorials.
01:05 Name it while hyphen loop dot rb.
01:09 I have a working example of the 'while' loop.
01:13 Now, let us switch to the terminal and type: gedit space while hyphen loop dot rb space & (ampersand)
01:24 You can pause the tutorial, type the code as we go through it.
01:28 I have declared a while loop in this example.
01:32 First, I declared a local variable 'i' and initialized it with value 0.
01:38 Then I declare a 'while' loop.
01:41 This loop will execute as long as the variable 'i' is greater than -10.
01:46 The puts method, declared within the while loop, will display the output.
01:51 After the output is displayed, we decrement the value of 'i' by 1.
01:56 'i' will adopt this decremented value before the next iteration.
02:01 The variable 'i' gets decremented in every iteration.
02:04 This goes on till 'i' reaches the value -10.
02:09 At this point, the 'while' condition fails.
02:12 It subsequently breaks out of the loop and stops printing the output.
02:16 Now, let us switch to the terminal and type: ruby space while hyphen loop dot rb and see the output.
02:30 The output will consist of a list of numbers 0 through -9.
02:35 You should now be able to write your own while loop in Ruby.
02:40 Let's look at the until loop next.
02:43 The syntax for the until loop in Ruby is -
02:45 until “boolean expression”
02:47 ruby code , end
02:50 Let us look at an example.
02:52 Now,let us switch to the terminal and type: gedit space until hyphen loop dot rb space & (ampersand)
03:03 You can pause the tutorial and type the code as we go through it.
03:07 I have declared an until loop in this example.
03:12 We had declared a local variable 'i' and initialized it to 0.
03:16 Then we declare an until loop.
03:18 This loop will execute as long as the variable 'i' is greater than -10.
03:23 The 'puts' method will display the output.
03:27 After the output is displayed, value of 'i' is decremented by 1.
03:32 'i' will adopt this decremented value before the next iteration.
03:36 The variable 'i' gets decremented during every iteration.
03:40 This goes on till 'i' reaches the value -11.
03:43 At this point, the 'until' condition fails.
03:46 Subsequently, it breaks out of the loop and stops printing the output.
03:51 Now, switch to the terminal and type: ruby space until hyphen loop dot rb and see the output.
04:03 The output will consist of a list of numbers 0 through -10.
04:08 You should now be able to write your own until loop in Ruby.
04:13 Let's now move on to the redo construct.
04:16 The syntax for redo in Ruby is as follows:
04:20 a collection of objects. each do item
04:25 a conditional statement
04:27 ruby code , redo
04:29 end conditional, end loop
04:32 I have a working example of the redo loop.
04:35 Now, let us switch to the terminal and type: gedit space redo hyphen loop dot rb space &(ampersand )
04:48 You can pause the tutorial and type the code as we go through it.
04:52 I have declared an each loop in this example.
04:55 We have declared an each loop to iterate through numbers 10 to 20.
05:00 Then, we define an if conditional statement.
05:04 The loop will execute for every number between 10 to 20.
05:08 It will enter the inner conditional if conditional block only if the value of 'i' is equal to 20.
05:15 The 'puts' method, declared within the each loop, displays the output.
05:20 Once the program enters the 'if' conditional block, it will first print the output.
05:24 Then it will execute redo.
05:28 redo will execute the iteration of the most internal loop.
05:31 It will do so, without checking the loop condition.
05:34 Our condition being if i == 20,
05:38 the result will be an infinite loop, since the value of 'i' will not change from 20.
05:43 Let's switch to the terminal and type: ruby space redo hyphen loop dot rb
05:52 and see the output. The output will consist of an infinite loop that never ends.
05:58 Press Ctrl + C to terminate the infinite loop.
06:03 Now, let us look at the break statement.
06:06 The syntax for the break statement in Ruby is -
06:10 a looping statement
06:12 a conditional statement , break
06:14 end conditional
06:16 ruby code, end loop
06:18 Let us look at an example.
06:21 Now, let us switch to the terminal and type: gedit space break hyphen loop dot rb space ampersand.
06:33 You can pause the tutorial and type the code as we go through this example.
06:38 I have declared an each loop in this example.
06:41 It is similar to the one we used earlier.
06:43 The 'puts' method here, will display the output for numbers 11 to 19.
06:49 Once the value becomes 20, the program enters the conditional 'if' block.
06:54 At this point, it will encounter the break statement and breaks out of the loop.
06:59 Now, open the terminal and type:
07:02 ruby space break hyphen loop dot rb
07:05 and see the output.
07:08 The output will consist of numbers 10 through 19.
07:13 Now, you should be able to create your own break construct.
07:17 This brings us to the end of this Spoken Tutorial.
07:20 Let's summarize.
07:22 In this tutorial, we have learnt to use:
07:24 while loop, until construct
07:26 redo, break construct.
07:29 As an assignment-
07:31 Consider a range of numbers 100 to 115(inclusive), represented as Fahrenheit.
07:38 Write a Ruby program using
07:40 the appropriate loop construct
07:42 that uses the Fahrenheit to Celsius conversion formula
07:46 against the given range of numbers.
07:49 to display the output: “The temperature has reached a certain degree Celsius and has become unbearable”
07:55 when the temperature in Celsius is above 32 degree Celsius.
08:00 Watch the video available at the following link.
08:03 It summarizes the Spoken Tutorial project.
08:07 If you do not have good bandwidth, you can download and watch it.
08:10 The Spoken Tutorial project team:
08:13 Conducts workshops using spoken tutorials.
08:15 Gives certificates to those who pass an online test.
08:19 For more details, please write to: contact@spoken-tutorial.org
08:25 Spoken Tutorial project is a part of the Talk to a Teacher project.
08:29 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
08:35 More information on this mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
08:44 This is Anjana Nair, signing off. Thank you.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14

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