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

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

| In this tutorial, we will learn:

|Meaning of the term ''' “loop” '''. The different kinds of loops in '''Ruby '''

|Usage of ''' “for” ''' loop and Usage of ''' “each” ''' looping construct.  

|Here, we are using:

| ''' Ubuntu''' version '''12.04'''

|''' Ruby 1.9.3 '''

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

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

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

| 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.  

| Ruby has the following main looping statements.  

| '''for''', '''each ''',  ''' while''', '''until'''.

|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-

| '''ttt,  ruby hyphen tutorial, looping hyphen statements'''.  

| Please create the sub-folders as mentioned there.

|Now we have created the requisite folders.  

|Let's move ahead.  

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

|''' ruby code ''' ''' end '''

| Let us try to understand it with an example.  

| Create a new file in '''gedit''' as shown in the basic level ''' Ruby tutorials'''  

|and name it '''for hyphen loop dot rb '''.

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

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

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

|  We have a set of numbers 1 to 20.  

| 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 ''' “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.  

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

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

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

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

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

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

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

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

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

| ''' ruby code''' '''end'''

| Create a new file in '''gedit''' as shown in the basic level '''Ruby tutorials'''  

|and name it '''each hyphen loop dot rb'''.

|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''' loop, is responsible for generating the output.  

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

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

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

| '''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.  

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

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

|How would we determine which looping '''construct''' to choose?  

|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''' loop.  

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

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

|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.  

|In this tutorial, we have learnt: Usage of ''' for''' loop  

| Usage of  '''each''' construct  

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

| Examples of using the above looping constructs.

| As an assignment-

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

|It summarizes the Spoken Tutorial project.

| The Spoken Tutorial project team:

| Conducts workshops using spoken tutorials.

| Gives certificates to those who pass an online test.

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

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

|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.