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.  

| Welcome to the tutorial on '''while''' and '''until loops''' in Ruby.  

|-

|-

| In this tutorial we will learn to use-  

| In this tutorial we will learn to use-  

|-

|-

| '''while loop '''

| '''while loop '''

|-

|-

|'''until loop '''

|'''until loop '''

|-

|-

| '''redo'''

| '''redo'''

|-

|-

|and '''break'''   

|and '''break'''   

|-

|-

|We are using  

|We are using  

|-

|-

|  ''' Ubuntu''' version 12.04  

|  ''' Ubuntu''' version 12.04  

|-

|-

|''' Ruby '''1.9.3  

|''' Ruby '''1.9.3  

|-

|-

|To follow this tutorial, you must have ''' Internet''' Connection.   

|To follow this tutorial, you must have ''' Internet''' Connection.   

    

    

|-

|-

| You must also have knowledge of '''Linux'''  commands, ''' Terminal''' and ''' Text-editor.'''

| You must also have knowledge of '''Linux'''  commands, ''' Terminal''' and ''' Text-editor.'''

|-

|-

|If not, for relevant tutorials, please visit our website.  

|If not, for relevant tutorials, please visit our website.  

|-

|-

|  Before we begin, recall that we had created ''' ttt''' directory earlier.  

|  Before we begin, recall that we had created ''' ttt''' directory earlier.  

|-

|-

|Let's go to that directory.  

|Let's go to that directory.  

|-

|-

|Then to ''' ruby hyphen tutorial''' and '''looping hyphen statements''' directory.   

|Then to ''' ruby hyphen tutorial''' and '''looping hyphen statements''' directory.   

|-

|-

|Now that we are in that folder, let’s move ahead.  

|Now that we are in that folder, let’s move ahead.  

|-

|-

| The syntax of the '''while''' loop in ''' Ruby''' is as follows:  

| The syntax of the '''while''' loop in ''' Ruby''' is as follows:  

|-

|-

|''' while “boolean expression” '''

|''' while “boolean expression” '''

|-

|-

|''' ruby code '''

|''' ruby code '''

|-

|-

|'''end'''  

|'''end'''  

|-

|-

| Let us look at an example.  

| Let us look at an example.  

|-

|-

| 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.   

|-

|-

| Name it ''' while hyphen loop dot rb '''

| Name it ''' while hyphen loop dot rb '''

|-

|-

|I have a working example of the ''' while  loop'''.  

|I have a working example of the ''' while  loop'''.  

|-

|-

|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)

|-

|-

|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.  

   

   

|-

|-

|I have declared a ''' while''' loop in this example.  

|I have declared a ''' while''' loop in this example.  

|-

|-

| 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.  

|-

|-

|Then I declare a ''' while loop. '''

|Then I declare a ''' while loop. '''

|-

|-

| 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.  

|-

|-

| The '''puts''' method is declared within the ''' while''' loop will display the output.  

| The '''puts''' method is declared within the ''' while''' loop will display the output.  

|-

|-

| 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.  

|-

|-

|'''i''' will adopt this decremented value before the next iteration.  

|'''i''' will adopt this decremented value before the next iteration.  

|-

|-

|The variable ''' i ''' gets decremented in every iteration.   

|The variable ''' i ''' gets decremented in every iteration.   

|-

|-

|This goes on till '''i''' reaches the value -10,  

|This goes on till '''i''' reaches the value -10,  

|-

|-

|  At this point the '''while condition''' fails.  

|  At this point the '''while condition''' fails.  

|-

|-

| It subsequently breaks out of the loop and stops printing the output.  

| It subsequently breaks out of the loop and stops printing the output.  

|-

|-

| 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.  

|-

|-

|The output will consist of a list of numbers 0 through -9.  

|The output will consist of a list of numbers 0 through -9.  

|-

|-

| 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.  '''

|-

|-

| Let's look at the '''until''' loop next.

| Let's look at the '''until''' loop next.

|-

|-

|The syntax for the '''until''' loop in '''Ruby''' is -  

|The syntax for the '''until''' loop in '''Ruby''' is -  

|-

|-

|''' until “boolean expression”'''

|''' until “boolean expression”'''

|-

|-

|''' ruby code '''

|''' ruby code '''

|-

|-

| '''end'''

| '''end'''

|-

|-

| Let us look at an example.  

| Let us look at an example.  

|-

|-

| Now let us switch to a '''terminal''' and type ''' gedit space until hyphen loop dot rb space &''' (ampersand)

| Now let us switch to a '''terminal''' and type ''' gedit space until hyphen loop dot rb space &''' (ampersand)

|-

|-

|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.  

|-

|-

| I have declared an ''' until''' loop in this example.  

| I have declared an ''' until''' loop in this example.  

|-

|-

|We had declared a local variable ''' i''' and initialized it to 0.  

|We had declared a local variable ''' i''' and initialized it to 0.  

|-

|-

| Then we declare an ''' until''' loop.  

| Then we declare an ''' until''' loop.  

|-

|-

|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.  

|-

|-

|The '''puts''' method will display the output.  

|The '''puts''' method will display the output.  

|-

|-

| After the output is displayed, value of '''i''' is decremented by 1.   

| After the output is displayed, value of '''i''' is decremented by 1.   

|-

|-

|'''i''' will adopt this decremented value before the next iteration.  

|'''i''' will adopt this decremented value before the next iteration.  

|-

|-

| The variable '''i''' gets decremented during every iteration.  

| The variable '''i''' gets decremented during every iteration.  

|-

|-

|  This goes on till '''i''' reaches the value -11.  

|  This goes on till '''i''' reaches the value -11.  

|-

|-

|At this point the '''until condition''' fails.   

|At this point the '''until condition''' fails.   

|-

|-

| Subsequently, it breaks out of the loop and stops printing the output.  

| Subsequently, it breaks out of the loop and stops printing the output.  

|-

|-

|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.  

|-

|-

| The output will consist of a list of numbers 0 through -10.  

| The output will consist of a list of numbers 0 through -10.  

|-

|-

|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.'''   

|-

|-

|Let's now move on to the '''redo''' construct.  

|Let's now move on to the '''redo''' construct.  

|-

|-

| The syntax for '''redo''' in ''' Ruby''' is as follows:  

| The syntax for '''redo''' in ''' Ruby''' is as follows:  

|-

|-

|''' a collection of objects.each do item '''

|''' a collection of objects.each do item '''

|-

|-

| '''a conditional statement '''

| '''a conditional statement '''

|-

|-

|'''ruby code '''

|'''ruby code '''

|-

|-

|'''redo'''

|'''redo'''

|-

|-

|'''end''' conditional

|'''end''' conditional

|-

|-

| '''end''' loop  

| '''end''' loop  

|-

|-

|I have a working example of the '''redo''' loop.   

|I have a working example of the '''redo''' loop.   

|-

|-

|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 )

|-

|-

| 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.  

|-

|-

|I have declared an '''each''' loop in this example.  

|I have declared an '''each''' loop in this example.  

|-

|-

| 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.  

|-

|-

| Then, we define an ''' if''' conditional statement.  

| Then, we define an ''' if''' conditional statement.  

|-

|-

| The loop will execute for every number between 10 to 20.  

| The loop will execute for every number between 10 to 20.  

|-

|-

| 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.   

|-

|-

|The '''puts''' method declared within the '''each''' loop displays the output.  

|The '''puts''' method declared within the '''each''' loop displays the output.  

|-

|-

| 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.  

|-

|-

|Then it will execute '''redo. '''

|Then it will execute '''redo. '''

|-

|-

|'''redo''' will execute the iteration of the most internal loop.   

|'''redo''' will execute the iteration of the most internal loop.   

|-

|-

|It will do so without checking the loop condition.  

|It will do so without checking the loop condition.  

   

   

|-

|-

|Our condition being ''' if i == 20. '''

|Our condition being ''' if i == 20. '''

|-

|-

| 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.   

|-

|-

|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'''

|-

|-

|and see the output.  

|and see the output.  

|-

|-

|The output will consist of an infinite loop that never ends.  

|The output will consist of an infinite loop that never ends.  

|-

|-

|Press '''Ctrl + C''' to terminate the infinite loop  

|Press '''Ctrl + C''' to terminate the infinite loop  

|-

|-

| Now, let us look at the '''break'''  statement.  

| Now, let us look at the '''break'''  statement.  

|-

|-

|The syntax for the '''break''' statement in '''Ruby''' is -   

|The syntax for the '''break''' statement in '''Ruby''' is -   

|-

|-

|'''a looping statement '''

|'''a looping statement '''

|-

|-

|  '''a conditional statement '''

|  '''a conditional statement '''

   

   

|-

|-

|'''break '''

|'''break '''

|-

|-

|'''end conditional '''

|'''end conditional '''

|-

|-

|'''ruby code'''

|'''ruby code'''

|-

|-

|'''end loop '''

|'''end loop '''

   

   

|-

|-

| Let us look at an example.  

| Let us look at an example.  

|-

|-

|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.'''

|-

|-

|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.  

|-

|-

|I have declared an '''each''' loop in this example.  

|I have declared an '''each''' loop in this example.  

|-

|-

|It is similar to the one we used earlier.  

|It is similar to the one we used earlier.  

|-

|-

|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.  

|-

|-

|Once the value becomes 20, the program enters the conditional '''if''' block.  

|Once the value becomes 20, the program enters the conditional '''if''' block.  

|-

|-

|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 break out of the loop.  

|-

|-

|Now open the '''terminal''' and type  

|Now open the '''terminal''' and type  

|-

|-

|'''ruby space break hyphen loop dot rb '''

|'''ruby space break hyphen loop dot rb '''

|-

|-

|and see the output.  

|and see the output.  

|-

|-

|The output will consist of numbers 10 through 19.  

|The output will consist of numbers 10 through 19.  

|-

|-

|Now you should be able to create your own '''break''' construct.  

|Now you should be able to create your own '''break''' construct.  

|-

|-

|This brings us to the end of this Spoken Tutorial.  

|This brings us to the end of this Spoken Tutorial.  

|-

|-

|Let's summarize.  

|Let's summarize.  

|-

|-

|In this tutorial we have learnt to use  

|In this tutorial we have learnt to use  

|-

|-

|'''while''' loop  

|'''while''' loop  

|-

|-

|'''until''' construct  

|'''until''' construct  

|-

|-

|'''redo'''

|'''redo'''

|-

|-

|'''break''' construct  

|'''break''' construct  

|-

|-

|As as assignment  

|As as assignment  

|-

|-

|Consider  a range of numbers 100 to 115(inclusive) represented as Fahrenheit.

|Consider  a range of numbers 100 to 115(inclusive) represented as Fahrenheit.

|-

|-

|Write a Ruby program using

|Write a Ruby program using

|-

|-

|the appropriate loop construct

|the appropriate loop construct

|-

|-

|that uses the Fahrenheit to Celsius conversion formula

|that uses the Fahrenheit to Celsius conversion formula

|-

|-

|against the given range of numbers

|against the given range of numbers

|-

|-

|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 Celcius and has become unbearable”'''

|-

|-

|when the temperature in Celcius is above 32 degree Celcius

|when the temperature in Celcius is above 32 degree Celcius

|-

|-

|  Watch the video available at the following link.

|  Watch the video available at the following link.

|-

|-

|It summarises the Spoken Tutorial project.

|It summarises the Spoken Tutorial project.

|-

|-

|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.  

|-

|-

|  The Spoken Tutorial Project Team :

|  The Spoken Tutorial Project Team :

|-   

|-   

|Conducts workshops using spoken tutorials  

|Conducts workshops using spoken tutorials  

|-

|-

|Gives certificates to those who pass an online test  

|Gives certificates to those who pass an online test  

|-

|-

|For more details, please write to contact@spoken-tutorial.org

|For more details, please write to contact@spoken-tutorial.org

|-

|-

|  Spoken Tutorial Project is a part of the Talk to a Teacher project.

|  Spoken Tutorial Project is a part of the Talk to a Teacher project.

|-

|-

|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.

|-

|-

|More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro

|More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro

|-

|-

| This is Anjana Nair signing off. Thank you

| This is Anjana Nair signing off. Thank you

|}

|}