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

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(Created page with ' {| border=1 || ''Time''' || '''Narration''' |- | 00.01 | Welcome to the tutorial on '''while''' and '''until loops''' in Ruby. |- | 00.06 | In this tutorial we will learn …')
 
 
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{| border=1
 
{| border=1
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|| ''Time'''
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| '''Time'''
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|| '''Narration'''
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| '''Narration'''
  
 
|-
 
|-
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|  00.01
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|  00:01
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| Welcome to the tutorial on '''while''' and '''until loops''' in Ruby.  
+
| Welcome to the tutorial on '''while and until loops''' in '''Ruby'''.  
  
 
|-
 
|-
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| 00.06
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| 00:06
−
| In this tutorial we will learn to use-  
+
| In this tutorial, we will learn to use-  
  
 
|-
 
|-
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| 00.09
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| 00:09
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| '''while''' loop  
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| ''''while' loop ''',  ''''until' loop '''
  
 
|-
 
|-
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| 00.10
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| 00:11
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|'''until''' loop
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| '''redo''' and '''break'''. 
  
 
|-
 
|-
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| 00.11
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| 00:13
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| '''redo'''
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| We are using:  ''' Ubuntu''' version '''12.04'''  
  
 
|-
 
|-
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| 00.12
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| 00:17
−
|and '''break'''
+
| '''Ruby 1.9.3'''
  
 
|-
 
|-
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| 00.13
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| 00:20
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|We are using
+
| To follow this tutorial, you must have ''' Internet''' connection.   
−
 
+
−
|-
+
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|  00.14
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−
|  ''' Ubuntu''' version 12.04
+
−
 
+
−
|-
+
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| 00.17
+
−
|''' Ruby '''1.9.3
+
−
 
+
−
|-
+
−
| 00.20
+
−
|To follow this tutorial, you must have ''' Internet''' Connection.   
+
 
    
 
    
−
 
 
|-
 
|-
−
|  00.25
+
|  00:25
 
| You must also have knowledge of '''Linux'''  commands, ''' Terminal''' and ''' Text-editor.'''
 
| You must also have knowledge of '''Linux'''  commands, ''' Terminal''' and ''' Text-editor.'''
−
 
−
 
  
 
|-
 
|-
−
| 00.29
+
| 00:29
 
|If not, for relevant tutorials, please visit our website.  
 
|If not, for relevant tutorials, please visit our website.  
  
 
|-
 
|-
−
|  00.34
+
|  00:34
 
|  Before we begin, recall that we had created ''' ttt''' directory earlier.  
 
|  Before we begin, recall that we had created ''' ttt''' directory earlier.  
  
 
|-
 
|-
−
| 00.38
+
| 00:38
 
|Let's go to that directory.  
 
|Let's go to that directory.  
  
 
|-
 
|-
−
| 00.41
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| 00:41
−
|Then to ''' ruby hyphen tutorial''' and '''looping hyphen statements''' directory.   
+
|Then to ''' ruby hyphen tutorial''' and '''looping hyphen statements''' directories.   
  
 
|-
 
|-
−
| 00.46
+
| 00:46
 
|Now that we are in that folder, let’s move ahead.  
 
|Now that we are in that folder, let’s move ahead.  
  
 
|-
 
|-
−
| 00.50
+
| 00:50
 
| The syntax of the '''while''' loop in ''' Ruby''' is as follows:  
 
| The syntax of the '''while''' loop in ''' Ruby''' is as follows:  
  
 
|-
 
|-
−
| 00.54
+
| 00:54
 
|''' while “boolean expression” '''
 
|''' while “boolean expression” '''
  
 
|-
 
|-
−
|  00.56
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|  00:56
−
|''' ruby code '''
+
|''' ruby code ''', '''end'''  
−
 
+
−
|-
+
−
| 00.57
+
−
|'''end'''  
+
  
 
|-
 
|-
−
| 00.58
+
| 00:58
 
| Let us look at an example.  
 
| Let us look at an example.  
  
 
|-
 
|-
−
| 01.01
+
| 01:01
−
| Create a new file in '''gedit''' as shown in the basic level ''' Ruby''' tutorials.   
+
| Create a new file in '''gedit''' as shown in the basic level '''Ruby tutorials'''.   
  
 
|-
 
|-
−
| 01.05
+
| 01:05
−
| Name it ''' while-loop.rb '''
+
| Name it '''while hyphen loop dot rb.'''
  
 
|-
 
|-
−
| 01.09
+
| 01:09
−
|I have a working example of the ''' while''' loop.  
+
|I have a working example of the ''' 'while' loop'''.  
 
|-
 
|-
−
| 01.13
+
| 01:13
−
|Now let us switch to the terminal and type  ''' gedit space while hyphen loop dot rb space & (ampersand)'''
+
|Now, let us switch to the '''terminal''' and type: ''' gedit space while hyphen loop dot rb space &''' (ampersand)
  
 
|-
 
|-
−
| 01.24
+
| 01:24
 
|You can pause the tutorial, type the code as we go through it.  
 
|You can pause the tutorial, type the code as we go through it.  
 
   
 
   
 
|-
 
|-
−
| 01.28
+
| 01:28
 
|I have declared a ''' while''' loop in this example.  
 
|I have declared a ''' while''' loop in this example.  
−
 
  
 
|-
 
|-
−
|  01.32
+
|  01:32
−
| First, I declared a local variable '''i''' and initialized it with value 0.  
+
| First, I declared a local variable 'i' and initialized it with value 0.  
−
 
+
  
 
|-
 
|-
−
|  01.38
+
|  01:38
−
|Then I declare a ''' while''' loop.  
+
|Then I declare a ''''while' loop.'''
  
 
|-
 
|-
−
|  01.41
+
|  01:41
−
| This loop will execute as long as the variable ''' i''' is greater than -10.  
+
| This loop will execute as long as the variable 'i' is greater than -10.  
−
 
+
  
 
|-
 
|-
−
| 01.46
+
| 01:46
−
| The '''puts''' method is declared within the ''' while''' loop will display the output.  
+
| The '''puts''' '''method''', declared within the ''' while''' loop, will display the output.  
  
 
|-
 
|-
−
|  01.51
+
|  01:51
−
| After the output is displayed, we decrement the value of i by 1.  
+
| After the output is displayed, we decrement the value of 'i' by 1.  
  
 
|-
 
|-
−
| 01.56
+
| 01:56
−
|I will adopt this decremented value before the next iteration.  
+
|'i' will adopt this decremented value before the next iteration.  
−
 
+
  
 
|-
 
|-
−
| 02.01
+
| 02:01
−
|The variable ''' i ''' gets decremented in every iteration.   
+
|The variable 'i' gets decremented in every iteration.   
  
 
|-
 
|-
−
| 02.04
+
| 02:04
−
|This goes on till i reaches the value -10,
+
|This goes on till 'i' reaches the value -10.
  
 
|-
 
|-
−
|  02.09
+
|  02:09
−
|  At this point the '''while condition''' fails.  
+
|  At this point, the ''''while' condition''' fails.  
  
 
|-
 
|-
−
| 02.12
+
| 02:12
 
| It subsequently breaks out of the loop and stops printing the output.  
 
| It subsequently breaks out of the loop and stops printing the output.  
  
 
|-
 
|-
−
| 02.16
+
| 02:16
−
| Now, let us switch to the '''terminal''' and type '''ruby space while hyphen loop dot rb''' and see the output.  
+
| Now, let us switch to the '''terminal''' and type: '''ruby space while hyphen loop dot rb''' and see the output.  
−
 
+
  
 
|-
 
|-
−
|  02.30
+
|  02:30
 
|The output will consist of a list of numbers 0 through -9.  
 
|The output will consist of a list of numbers 0 through -9.  
  
 
|-
 
|-
−
|  02.35
+
|  02:35
−
| You should now be able to write your own '''while''' loop in '''Ruby. '''
+
| You should now be able to write your own '''while''' loop in Ruby.
  
 
|-
 
|-
−
|  02.40
+
|  02:40
 
| Let's look at the '''until''' loop next.
 
| Let's look at the '''until''' loop next.
  
 
|-
 
|-
−
| 02.43
+
| 02:43
−
|The syntax for the '''until''' loop in Ruby is -  
+
|The syntax for the '''until''' loop in '''Ruby''' is -  
  
 
|-
 
|-
−
|  02.45
+
|  02:45
 
|''' until “boolean expression”'''
 
|''' until “boolean expression”'''
  
 
|-
 
|-
−
| 02.47
+
| 02:47
−
|''' ruby code '''
+
|''' ruby code ''', '''end'''
−
 
+
−
|-
+
−
| 02.48
+
−
| '''end'''
+
  
 
|-
 
|-
−
| 02.50
+
| 02:50
 
| Let us look at an example.  
 
| Let us look at an example.  
  
 
|-
 
|-
−
| 02.52
+
| 02:52
−
| Now let us switch to a '''terminal''' and type ''' gedit space until hyphen loop dot rb space ampersand'''
+
| Now,let us switch to the '''terminal''' and type: ''' gedit space until hyphen loop dot rb space &''' (ampersand)
  
 
|-
 
|-
−
| 03.03
+
| 03:03
−
|You can pause the tutorial, and type the code as we go through it.  
+
|You can pause the tutorial and type the code as we go through it.  
  
 
|-
 
|-
−
|  03.07
+
|  03:07
 
| I have declared an ''' until''' loop in this example.  
 
| I have declared an ''' until''' loop in this example.  
  
 
|-
 
|-
−
| 03.12
+
| 03:12
−
|We had declared a local variable i and initialized it to 0.  
+
|We had declared a local variable 'i' and initialized it to 0.  
  
 
|-
 
|-
−
| 03.16
+
| 03:16
 
| Then we declare an ''' until''' loop.  
 
| Then we declare an ''' until''' loop.  
  
 
|-
 
|-
−
| 03.18
+
| 03:18
−
|This loop will execute as long as the variable i is greater than -10.  
+
|This loop will execute as long as the variable 'i' is greater than -10.  
  
 
|-
 
|-
−
| 03.23
+
| 03:23
−
|The '''puts''' method will display the output.  
+
|The ''''puts' method''' will display the output.  
  
 
|-
 
|-
−
| 03.27
+
| 03:27
−
| After the output is displayed, value of i is decremented by 1.   
+
| After the output is displayed, value of 'i' is decremented by 1.   
  
 
|-
 
|-
−
| 03.32
+
| 03:32
−
|'''i''' will adopt this decremented value before the next iteration.  
+
|'i' will adopt this decremented value before the next iteration.  
  
 
|-
 
|-
−
|  03.36
+
|  03:36
−
| The variable '''i''' gets decremented during every iteration.  
+
| The variable 'i' gets decremented during every iteration.  
  
 
|-
 
|-
−
|  03.40
+
|  03:40
−
|  This goes on till i reaches the value -11.  
+
|  This goes on till 'i' reaches the value -11.  
  
 
|-
 
|-
−
|  03.43
+
|  03:43
−
|At this point the '''until condition''' fails.   
+
|At this point, the ''''until' condition''' fails.   
  
 
|-
 
|-
−
|  03.47
+
|  03:46
 
| Subsequently, it breaks out of the loop and stops printing the output.  
 
| Subsequently, it breaks out of the loop and stops printing the output.  
  
 
|-
 
|-
−
| 03.51
+
| 03:51
−
|Now switch to the ''' terminal''' and type ''' ruby space until hyphen loop dot rb and see the output. '''
+
|Now, switch to the ''' terminal''' and type: ''' ruby space until hyphen loop dot rb''' and see the output.  
  
 
|-
 
|-
−
|  04.03
+
|  04:03
 
| The output will consist of a list of numbers 0 through -10.  
 
| The output will consist of a list of numbers 0 through -10.  
  
 
|-
 
|-
−
|  04.08
+
|  04:08
 
|You should now be able to write your own '''until''' loop in '''Ruby.'''   
 
|You should now be able to write your own '''until''' loop in '''Ruby.'''   
  
 
|-
 
|-
−
| 04.13
+
| 04:13
 
|Let's now move on to the '''redo''' construct.  
 
|Let's now move on to the '''redo''' construct.  
  
 
|-
 
|-
−
|  04.16
+
|  04:16
−
| The syntax for '''redo''' in ''' Ruby''' is as follows:  
+
| The syntax for '''redo''' in Ruby is as follows:  
  
 
|-
 
|-
−
| 04.20
+
| 04:20
−
|''' a collection of objects.each do |item| '''
+
|''' a collection of objects. each do item'''
  
 
|-
 
|-
−
| 04.25
+
| 04:25
−
| '''a conditional statement '''
+
| '''a conditional statement'''
  
 
|-
 
|-
−
| 04.27
+
| 04:27
−
|'''ruby code '''
+
|'''ruby code ''', '''redo'''
  
 
|-
 
|-
−
| 04.28
+
| 04:29
−
|'''redo'''
+
|'''end conditional''',  '''end''' loop
  
 
|-
 
|-
−
| 04.29
+
|  04:32
−
|'''end''' conditional
+
−
 
+
−
|-
+
−
|  04.30
+
−
| '''end''' loop
+
−
 
+
−
|-
+
−
|  04.32
+
 
|I have a working example of the '''redo''' loop.   
 
|I have a working example of the '''redo''' loop.   
  
 
|-
 
|-
−
|  04.35
+
|  04:35
−
|Now let us switch to the terminal and type gedit space redo hyphen loop dot rb space ampersand  
+
|Now, let us switch to the '''terminal''' and type: '''gedit space redo hyphen loop dot rb space &'''(ampersand )
  
 
|-
 
|-
−
| 04.48
+
| 04:48
−
| You can pause the tutorial, and type the code as we go through it.  
+
| You can pause the tutorial and type the code as we go through it.  
  
 
|-
 
|-
−
| 04.52
+
| 04:52
 
|I have declared an '''each''' loop in this example.  
 
|I have declared an '''each''' loop in this example.  
  
 
|-
 
|-
−
| 04.55
+
| 04:55
 
| We have declared an '''each''' loop to iterate through numbers 10 to 20.  
 
| We have declared an '''each''' loop to iterate through numbers 10 to 20.  
  
 
|-
 
|-
−
| 05.00
+
| 05:00
−
| Then, we define an ''' if''' conditional statement.  
+
| Then, we define an '''if''' conditional statement.  
−
 
+
  
 
|-
 
|-
−
| 05.04
+
| 05:04
 
| The loop will execute for every number between 10 to 20.  
 
| The loop will execute for every number between 10 to 20.  
  
 
|-
 
|-
−
| 05.08
+
| 05:08
−
| It will enter the inner conditional ''' if''' conditional block only if the value of i is equal to 20.   
+
| It will enter the inner conditional ''' if''' conditional block only if the value of 'i' is equal to 20.   
  
 
|-
 
|-
−
| 05.15
+
| 05:15
−
|The '''puts''' method declared within the '''each''' loop displays the output.  
+
|The ''''puts' method''', declared within the '''each''' loop, displays the output.  
  
 
|-
 
|-
−
| 05.20
+
| 05:20
−
| Once the program enters the ''' if''' conditional block, it will first print the output.  
+
| Once the program enters the 'if' conditional block, it will first print the output.  
  
 
|-
 
|-
−
| 05.24
+
| 05:24
−
|Then it will execute '''redo. '''
+
|Then it will execute '''redo.'''
  
 
|-
 
|-
−
| 05.28
+
| 05:28
 
|'''redo''' will execute the iteration of the most internal loop.   
 
|'''redo''' will execute the iteration of the most internal loop.   
  
 
|-
 
|-
−
| 05.31
+
| 05:31
−
|It will do so without checking the loop condition.  
+
|It will do so, without checking the '''loop condition'''.  
 
   
 
   
 
|-
 
|-
−
| 05.34
+
| 05:34
−
|Our condition being ''' if i == 20. '''
+
|Our condition being '''if i == 20''',
  
 
|-
 
|-
−
| 05.38
+
| 05:38
−
| The result will be an infinite loop, since the value of '''i''' will not change from 20.   
+
| the result will be an infinite loop, since the value of 'i' will not change from 20.   
  
 
|-
 
|-
−
|05.43
+
|05:43
−
|Let's switch to the terminal and type '''ruby space redo hyphen loop dot rb'''
+
|Let's switch to the '''terminal''' and type: '''ruby space redo hyphen loop dot rb'''
  
 
|-
 
|-
−
| 05.52
+
| 05:52
−
|and see the output.  
+
|and see the output. The output will consist of an '''infinite loop''' that never ends.  
  
 
|-
 
|-
−
| 05.53
+
| 05:58
−
|The output will consist of an infinite loop that never ends.  
+
|Press '''Ctrl + C''' to terminate the infinite loop.  
  
 
|-
 
|-
−
| 05.58
+
|  06:03
−
|Press '''Ctrl + C''' to terminate the infinite loop
+
−
 
+
−
|-
+
−
|  06.02
+
 
| Now, let us look at the '''break'''  statement.  
 
| Now, let us look at the '''break'''  statement.  
  
 
|-
 
|-
−
| 06.06
+
| 06:06
−
|The syntax for the '''break''' statement in '''Ruby''' is -   
+
|The syntax for the '''break''' statement in Ruby is -   
  
 
|-
 
|-
−
| 06.10
+
| 06:10
−
|'''a looping statement '''
+
| '''a looping statement'''
  
 
|-
 
|-
−
|  06.12
+
|  06:12
−
| '''a conditional statement '''
+
| '''a conditional statement ''', '''break '''
−
+
−
|-
+
−
| 06.13
+
−
|'''break '''
+
  
 
|-
 
|-
−
| 06.14
+
| 06:14
 
|'''end conditional '''
 
|'''end conditional '''
  
 
|-
 
|-
−
|  06.16
+
|  06:16
−
|'''ruby code'''
+
|'''ruby code''', '''end loop '''
−
 
+
−
|-
+
−
| 06.17
+
−
|'''end loop '''
+
 
   
 
   
−
 
 
|-
 
|-
−
| 06.18
+
| 06:18
 
| Let us look at an example.  
 
| Let us look at an example.  
  
 
|-
 
|-
−
|  06.21
+
|  06:21
−
|Now let us switch to the '''terminal''' and type '''gedit space break hyphen loop dot rb space ampersand.'''
+
|Now, let us switch to the '''terminal''' and type: '''gedit space break hyphen loop dot rb space ampersand.'''
−
 
+
  
 
|-
 
|-
−
| 06.33
+
| 06:33
−
|You can pause the tutorial, and type the code as we go through this example.  
+
|You can pause the tutorial and type the code as we go through this example.  
−
 
+
  
 
|-
 
|-
−
| 06.38
+
| 06:38
 
|I have declared an '''each''' loop in this example.  
 
|I have declared an '''each''' loop in this example.  
  
 
|-
 
|-
−
| 06.41
+
| 06:41
 
|It is similar to the one we used earlier.  
 
|It is similar to the one we used earlier.  
  
 
|-
 
|-
−
| 06.44
+
| 06:43
−
|The '''puts''' method here will display the output for numbers 11 to 19.  
+
|The ''''puts' method''' here, will display the output for numbers 11 to 19.  
  
 
|-
 
|-
−
| 06.49
+
| 06:49
−
|Once the value becomes 20, the program enters the conditional '''if''' block.  
+
|Once the value becomes 20, the program enters the conditional 'if' block.  
  
 
|-
 
|-
−
| 06.54
+
| 06:54
−
|At this point, it will encounter the '''break''' statement and break out of the loop.  
+
|At this point, it will encounter the '''break''' statement and breaks out of the loop.  
  
 
|-
 
|-
−
| 06.59
+
| 06:59
−
|Now open the '''terminal''' and type  
+
|Now, open the '''terminal''' and type:
  
 
|-
 
|-
−
| 07.02
+
| 07:02
 
|'''ruby space break hyphen loop dot rb '''
 
|'''ruby space break hyphen loop dot rb '''
  
 
|-
 
|-
−
| 07.05
+
| 07:05
 
|and see the output.  
 
|and see the output.  
  
 
|-
 
|-
−
| 07.08
+
| 07:08
 
|The output will consist of numbers 10 through 19.  
 
|The output will consist of numbers 10 through 19.  
−
 
−
 
  
 
|-
 
|-
−
| 07.13
+
| 07:13
−
|Now you should be able to create your own '''break''' construct.  
+
|Now, you should be able to create your own '''break''' construct.  
  
 
|-
 
|-
−
| 07.17
+
| 07:17
 
|This brings us to the end of this Spoken Tutorial.  
 
|This brings us to the end of this Spoken Tutorial.  
  
 
|-
 
|-
−
| 07.20
+
| 07:20
 
|Let's summarize.  
 
|Let's summarize.  
  
 
|-
 
|-
−
| 07.22
+
| 07:22
−
|In this tutorial we have learnt to use  
+
|In this tutorial, we have learnt to use:
−
 
+
  
 
|-
 
|-
−
| 07.24
+
| 07:24
−
|'''while''' loop  
+
|'''while''' loop,  '''until''' construct
  
 
|-
 
|-
−
| 07.25
+
| 07:26
−
|'''until''' construct  
+
| '''redo''',  '''break''' construct.
  
 
|-
 
|-
−
| 07.26
+
| 07:29
−
|'''redo'''
+
|As an assignment-
  
 
|-
 
|-
−
| 07.27
+
| 07:31
−
|'''break''' construct
+
|Consider a range of numbers 100 to 115(inclusive), represented as Fahrenheit.
  
 
|-
 
|-
−
| 07.29
+
| 07:38
−
|As as assignment
+
−
 
+
−
|-
+
−
| 07.31
+
−
|Consider  a range of numbers 100 to 115(inclusive) represented as Fahrenheit.
+
−
 
+
−
|-
+
−
| 07.38
+
 
|Write a Ruby program using
 
|Write a Ruby program using
  
 
|-
 
|-
−
| 07.40
+
| 07:40
 
|the appropriate loop construct
 
|the appropriate loop construct
  
 
|-
 
|-
−
| 07.42
+
| 07:42
 
|that uses the Fahrenheit to Celsius conversion formula
 
|that uses the Fahrenheit to Celsius conversion formula
  
 
|-
 
|-
−
| 07.46
+
| 07:46
−
|against the given range of numbers
+
|against the given range of numbers.
  
 
|-
 
|-
−
| 07.49
+
| 07:49
−
|To display the output: ''' “The temperature has reached a certain degree Celcius and has become unbearable”'''
+
|to display the output: ''' “The temperature has reached a certain degree Celsius and has become unbearable”'''
 +
 
 
|-
 
|-
−
| 07.55
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| 07:55
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|when the temperature in Celcius is above 32 degree Celcius
+
|when the temperature in Celsius is above 32 degree Celsius.
  
 
|-
 
|-
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|  08.00
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|  08:00
 
|  Watch the video available at the following link.
 
|  Watch the video available at the following link.
  
 
|-
 
|-
−
| 08.03
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| 08:03
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|It summarises the Spoken Tutorial project.
+
|It summarizes the Spoken Tutorial project.
  
 
|-
 
|-
−
| 08.07
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| 08:07
 
|If you do not have good bandwidth, you can download and  watch it.  
 
|If you do not have good bandwidth, you can download and  watch it.  
  
 
|-
 
|-
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|  08.10
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|  08:10
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|  The Spoken Tutorial Project Team :
+
|  The Spoken Tutorial project team:
  
 
|-   
 
|-   
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| 08.13
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| 08:13
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|Conducts workshops using spoken tutorials  
+
| Conducts workshops using spoken tutorials.
  
 
|-
 
|-
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|08.15
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|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.
  
 
|-
 
|-
−
| 08.19
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| 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'''
  
 
|-
 
|-
−
|  08.25
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|  08:25
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|  Spoken Tutorial Project is a part of the Talk to a Teacher project.
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|  '''Spoken Tutorial''' project is a part of the '''Talk to a Teacher''' project.
  
 
|-
 
|-
−
| 08.29
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| 08:29
 
|It is supported by the National Mission on Education through ICT, MHRD, Government of India.
 
|It is supported by the National Mission on Education through ICT, MHRD, Government of India.
  
 
|-
 
|-
−
| 08.35
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| 08:35
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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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| 08.44
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| 08:44
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| This is Anjana Nair signing off. Thank you
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| This is Anjana Nair, signing off. Thank you.
  
 
|}
 
|}

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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