Difference between revisions of "Ruby/C3/for-and-each-Looping-Statements/English-timed"

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|| '''Narration'''

|| '''Narration'''

|-

|-

| Welcome to the tutorial on '''for''' and '''each Loops''' in Ruby.  

| Welcome to the tutorial on '''for''' and '''each Loops''' in Ruby.  

|-

|-

| In this tutorial we will learn  

| In this tutorial we will learn  

|-

|-

| Meaning of the term ''' “loop” '''

| Meaning of the term ''' “loop” '''

|-

|-

|The different kinds of loops in '''Ruby '''

|The different kinds of loops in '''Ruby '''

|-

|-

| Usage of ''' “for” ''' loop and  

| Usage of ''' “for” ''' loop and  

|-

|-

|Usage of ''' “each” ''' looping construct  

|Usage of ''' “each” ''' looping construct  

|-

|-

|Here we are using  

|Here 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.  

|-

|-

|  Now let me explain what is referred to as a ''' “loop” ''' in '''Ruby. '''

|  Now let me explain what is referred to as a ''' “loop” ''' in '''Ruby. '''

|-

|-

|A '''loop''' is a command or set of commands that are executed a fixed number of times.  

|A '''loop''' is a command or set of commands that are executed a fixed number of times.  

|-

|-

|''' Ruby''' has the following main looping statements.  

|''' Ruby''' has the following main looping statements.  

|-

|-

|'''for'''

|'''for'''

|-

|-

| '''each '''

| '''each '''

|-

|-

|''' while'''

|''' while'''

|-

|-

| '''until'''

| '''until'''

|-

|-

|In this tutorial we will learn how to use the '''for''' and ''' each''' looping constructs.  

|In this tutorial we will learn how to use the '''for''' and ''' each''' looping constructs.  

|-

|-

| Before we begin, please create the following folders in your home directory,  

| Before we begin, please create the following folders in your home directory,  

|-

|-

| ttt,  ruby hyphen tutorial, looping hyphen statements.  

| ttt,  ruby hyphen tutorial, looping hyphen statements.  

|-

|-

| Please create the sub folders as mentioned there

| Please create the sub folders as mentioned there

|-

|-

|Now we have created the requisite folders.  

|Now we have created the requisite folders.  

|-

|-

|Let's move ahead.  

|Let's move ahead.  

|-

|-

|The syntax of the ''' “for” ''' loop in ''' Ruby''' is as follows:  

|The syntax of the ''' “for” ''' loop in ''' Ruby''' is as follows:  

|-

|-

| ''' for “variable” in “a collection of objects” '''

| ''' for “variable” in “a collection of objects” '''

|-

|-

|''' ruby code '''

|''' ruby code '''

|-

|-

| ''' end '''

| ''' end '''

|-

|-

| Let us try to understand it with an example.  

| Let us try to understand it with 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.  

|-

|-

|And name it ''' “for hyphen loop dot rb” '''

|And name it ''' “for hyphen loop dot rb” '''

|-

|-

|I already have a working example of the ''' “for” ''' loop.  

|I already have a working example of the ''' “for” ''' loop.  

|-

|-

|You can type the code as we go through this example.  

|You can type the code as we go through this example.  

|-

|-

|  I have declared a ''' “for” ''' loop in this example.  

|  I have declared a ''' “for” ''' loop in this example.  

|-

|-

|  We have a set of numbers 1 to 20.  

|  We have a set of numbers 1 to 20.  

|-

|-

| We declare a variable called “i” within the ''' “for” ''' loop.  

| We declare a variable called “i” within the ''' “for” ''' loop.  

|-

|-

|The variable “i” gets initialized to the first element in the set of numbers 1 to 20.  

|The variable “i” gets initialized to the first element in the set of numbers 1 to 20.  

|-

|-

| The ''' “for” '''  loop declaration causes the code to iterate over each element in the set 1 to 20.  

| The ''' “for” '''  loop declaration causes the code to iterate over each element in the set 1 to 20.  

|-

|-

| The ''' “puts” ''' method declared within the ''' “for” ''' loop is responsible for generating the output.  

| The ''' “puts” ''' method declared within the ''' “for” ''' loop is responsible for generating the output.  

|-

|-

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

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

|-

|-

| ''' ruby space  for hyphen loop dot rb ''' and see the output

| ''' ruby space  for hyphen loop dot rb ''' and see the output

|-

|-

|The output will be an '''array''' of numbers 1 to 20.  

|The output will be an '''array''' of numbers 1 to 20.  

|-

|-

| In this example, we declared a  ''' “for”''' loop for an inclusive range.  

| In this example, we declared a  ''' “for”''' loop for an inclusive range.  

|-

|-

| It included all numbers from 1 to 20.  

| It included all numbers from 1 to 20.  

|-

|-

| Next,  we shall look at implementing the ''' “for”''' loop for a non-inclusive range.  

| Next,  we shall look at implementing the ''' “for”''' loop for a non-inclusive range.  

|-

|-

|Continue to type the next part of the code.  

|Continue to type the next part of the code.  

|-

|-

|Non-inclusive means it will not include the last element in the collection of objects.  

|Non-inclusive means it will not include the last element in the collection of objects.  

|-

|-

|Here ''' “for”''' loop is implemented for a non-inclusive range of numbers 1 to 20.  

|Here ''' “for”''' loop is implemented for a non-inclusive range of numbers 1 to 20.  

|-

|-

| You will notice shortly that the number 20 will not be printed in the output.  

| You will notice shortly that the number 20 will not be printed in the output.  

|-

|-

|The last digit does not get included when you have 3 dots between numbers.  

|The last digit does not get included when you have 3 dots between numbers.  

|-

|-

| Now open the ''' terminal''' and type ''' ruby space for hyphen loop dot rb'''

| Now open the ''' terminal''' and type ''' ruby space for hyphen loop dot rb'''

|-

|-

|and see the output.  

|and see the output.  

|-

|-

|The output will still be an ''' array''' of numbers but will not include the number 20.  

|The output will still be an ''' array''' of numbers but will not include the number 20.  

|-

|-

| Now, you should be capable enough to write your own ''' “for”'''  loop.  

| Now, you should be capable enough to write your own ''' “for”'''  loop.  

|-

|-

|The syntax of the ''' “each”''' loop in ''' Ruby''' is as follows:  

|The syntax of the ''' “each”''' loop in ''' Ruby''' is as follows:  

|-

|-

| ''' “a collection of objects” dot each do item '''

| ''' “a collection of objects” dot each do item '''

|-

|-

| ''' ruby code end'''

| ''' ruby code end'''

|-

|-

|Let us try to understand it with an example.  

|Let us try to understand it with 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.  

|-

|-

|And name it '''each hyphen loop dot rb'''

|And name it '''each hyphen loop dot rb'''

|-

|-

|I already have a working example of the '''each''' loop.  

|I already have a working example of the '''each''' loop.  

|-

|-

|You can type the code as we go through this example.  

|You can 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.  

|-

|-

|  We have a set of numbers 1 to 20.  

|  We have a set of numbers 1 to 20.  

|-

|-

|We declare a variable called “i” within the '''each''' loop.  

|We declare a variable called “i” within the '''each''' loop.  

|-

|-

| The “i” variable gets initialized to the first element in the set of numbers 1 to 20.  

| The “i” variable gets initialized to the first element in the set of numbers 1 to 20.  

|-

|-

|The '''each''' loop declaration causes the code to iterate over each element in the set 1 to 20.  

|The '''each''' loop declaration causes the code to iterate over each element in the set 1 to 20.  

|-

|-

|The ''' puts''' method declared within the ''' each'''  is responsible for generating the output.  

|The ''' puts''' method declared within the ''' each'''  is responsible for generating the output.  

|-

|-

|Now open the ''' terminal''' and type ''' ruby space each hyphen loop dot rb '''

|Now open the ''' terminal''' and type ''' ruby space each hyphen loop dot rb '''

|-

|-

| and see the output.  

| and see the output.  

|-

|-

|The output will be an array of numbers 1 to 20.  

|The output will be an array of numbers 1 to 20.  

|-

|-

| In the above example we declared an ''' each''' loop for an inclusive range.  

| In the above example we declared an ''' each''' loop for an inclusive range.  

|-

|-

|It included all numbers from 1 to 20.  

|It included all numbers from 1 to 20.  

|-

|-

| Next we shall look at implementing the '''each''' loop for a non-inclusive range.  

| Next we shall look at implementing the '''each''' loop for a non-inclusive range.  

|-

|-

|Continue to type this part of the code.  

|Continue to type this part of the code.  

|-

|-

| Non-inclusive means it will not include the last element in the collection of objects.  

| Non-inclusive means it will not include the last element in the collection of objects.  

|-

|-

| Here an '''each''' loop is implemented for a non-inclusive range of numbers 1 to 20.  

| Here an '''each''' loop is implemented for a non-inclusive range of numbers 1 to 20.  

|-

|-

| You will notice shortly that the number 20 will not be printed in the output.  

| You will notice shortly that the number 20 will not be printed in the output.  

|-

|-

| The last digit does not get included when you have 3 dots between numbers.  

| The last digit does not get included when you have 3 dots between numbers.  

|-

|-

|Now open the '''terminal''' and type '''ruby space each hyphen loop dot rb'''

|Now open the '''terminal''' and type '''ruby space each hyphen loop dot rb'''

|-

|-

| and see the output.  

| and see the output.  

|-

|-

|Now you should be capable enough to write your own '''each''' loop.  

|Now you should be capable enough to write your own '''each''' loop.  

|-

|-

|How would we determine which looping construct to choose?  

|How would we determine which looping construct to choose?  

|-

|-

|Let us try to recall the '''for''' loop construct.  

|Let us try to recall the '''for''' loop construct.  

   

   

|-

|-

|In the first example, we iterated over a set of numbers from 1 to 20 using '''for'''.  

|In the first example, we iterated over a set of numbers from 1 to 20 using '''for'''.  

|-

|-

| Execute ''' ruby space for hyphen loop dot rb''' in your terminal see the output.   

| Execute ''' ruby space for hyphen loop dot rb''' in your terminal see the output.   

|-

|-

| Now look at the code in '''gedit.'''  

| Now look at the code in '''gedit.'''  

|-

|-

|When you invoke the '''for loop''', '''Ruby''' is actually calling the '''each''' method behind the scenes.  

|When you invoke the '''for loop''', '''Ruby''' is actually calling the '''each''' method behind the scenes.  

|-

|-

|And calling '''each''' or '''for''' will generate the same output.  

|And calling '''each''' or '''for''' will generate the same output.  

|-

|-

|Since the call to '''for''' in turn calls ''' each''', it is preferable to use the '''each''' loop instead.   

|Since the call to '''for''' in turn calls ''' each''', it is preferable to use the '''each''' loop instead.   

|-

|-

| 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

|In this tutorial we have learnt

|-

|-

|  Usage of ''' for''' loop  

|  Usage of ''' for''' loop  

   

   

|-

|-

|Usage of  '''each''' construct  

|Usage of  '''each''' construct  

|-

|-

|Reasoning behind using '''each''' instead of '''for'''  

|Reasoning behind using '''each''' instead of '''for'''  

|-

|-

|Examples of using the above looping constructs  

|Examples of using the above looping constructs  

|-

|-

| As an assignment  

| As an assignment  

|-

|-

|Write a ruby program using the appropriate loop construct  

|Write a ruby program using the appropriate loop construct  

|-

|-

|to create an output of even numbers from a set of numbers, say 1 to 20

|to create an output of even numbers from a set of numbers, say 1 to 20

|-

|-

|  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

|}

|}