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| | '''Author: Anjana Nair''' | | '''Author: Anjana Nair''' |
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| | '''Keywords: for, each, loop, Ruby, video tutorial''' | | '''Keywords: for, each, loop, Ruby, video tutorial''' |
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| − | | + | || '''Visual Cue''' |
| − | {| style="border-spacing:0;" | + | || '''Narration''' |
| − | | style="border-top:1pt solid #000000;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| <center>'''Visual Cue'''</center> | + | |
| − | | style="border:1pt solid #000000;padding:0.097cm;"| <center>'''Narration'''</center> | + | |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 1
| + | | Slide 1 |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Welcome to the tutorial on '''for '''and '''each Loops''' in '''Ruby'''.
| + | | Welcome to the tutorial on '''for '''and '''each Loops''' in '''Ruby'''. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 2
| + | | Slide 2 |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| In this tutorial we will learn
| + | | In this tutorial we will learn |
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| | * Meaning of the term “loop” | | * Meaning of the term “loop” |
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| | * Usage of “'''for'''” loop and | | * Usage of “'''for'''” loop and |
| | * Usage of “'''each'''” looping construct | | * Usage of “'''each'''” looping construct |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 3
| + | | Slide 3 |
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| | System Requirements | | System Requirements |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Here we are using
| + | | Here we are using |
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| | * '''Ubuntu''' version 12.04 | | * '''Ubuntu''' version 12.04 |
| | * '''Ruby''' 1.9.3 | | * '''Ruby''' 1.9.3 |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 4
| + | | Slide 4 |
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| | Pre-requisites | | Pre-requisites |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| To follow this tutorial, you must have '''Internet''' Connection.
| + | | To follow this tutorial, you must have '''Internet''' Connection. |
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| | You must also have knowledge of '''Linux''' commands, '''Terminal''' and '''Text-editor.''' | | You must also have knowledge of '''Linux''' commands, '''Terminal''' and '''Text-editor.''' |
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| | If not, for relevant tutorials, please visit our website. | | If not, for relevant tutorials, please visit our website. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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'''. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 5
| + | | Slide 5 |
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| | What is a loop? | | What is a loop? |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 6
| + | | Slide 6 |
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| | Looping statements | | Looping statements |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| '''Ruby''' has the following main looping statements.
| + | | '''Ruby''' has the following main looping statements. |
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| | * '''for ''' | | * '''for ''' |
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| | * '''while''' | | * '''while''' |
| | * '''until ''' | | * '''until ''' |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to gedit
| + | | Switch to gedit |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Click on “'''dash-home'''” and type '''gedit''' to invoke the editor.
| + | | Click on “'''dash-home'''” and type '''gedit''' to invoke the editor. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to terminal
| + | | Switch to terminal |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Similarly, click on “'''dash-home'''” and select '''Terminal''' to open the '''terminal'''.
| + | | Similarly, click on “'''dash-home'''” and select '''Terminal''' to open the '''terminal'''. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Type mkdir ttt and press Enter
| + | | Type mkdir ttt and press Enter |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| In the '''terminal,''' type “'''mkdir ttt'''”.
| + | | In the '''terminal,''' type “'''mkdir ttt'''”. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Type cd ttt and press Enter
| + | | Type cd ttt and press Enter |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Then “'''cd'''” into that directory.
| + | | Then “'''cd'''” into that directory. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Type mkdir ruby-tutorial and press Enter
| + | | Type mkdir ruby-tutorial and press Enter |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Then type “'''mkdir ruby-tutorial'''”,
| + | | Then type “'''mkdir ruby-tutorial'''”, |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Type cd ruby-tutorial and press Enter
| + | | Type cd ruby-tutorial and press Enter |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| And then “'''cd''' '''ruby-tutorial'''”.
| + | | And then “'''cd''' '''ruby-tutorial'''”. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Type mkdir looping-statements and press Enter
| + | | Type mkdir looping-statements and press Enter |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Then type “'''mkdir looping-statements'''”
| + | | Then type “'''mkdir looping-statements'''” |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Type cd looping-statements and press Enter
| + | | Type cd looping-statements and press Enter |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| And then “'''cd looping-statements'''”
| + | | And then “'''cd looping-statements'''” |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Now we have created the requisite folders.
| + | | Now we have created the requisite folders. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 7
| + | | Slide 7 |
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| | “for” loop | | “for” loop |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The syntax of the “'''for'''” loop in '''Ruby''' is as follows:
| + | | The syntax of the “'''for'''” loop in '''Ruby''' is as follows: |
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| | '''for “variable” in “a collection of objects”''' | | '''for “variable” in “a collection of objects”''' |
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| | '''end''' | | '''end''' |
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| | Let us try to understand it with an example. | | Let us try to understand it with an example. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to gedit where you have already opened the file “for-loop.rb” with the '''for loop '''code typed inside.
| + | | Switch to gedit where you have already opened the file “for-loop.rb” with the '''for loop '''code typed inside. |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| | And name it “'''for-loop.rb'''” | | And name it “'''for-loop.rb'''” |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| I already have a working example of the “'''for”''' loop.
| + | | I already have a working example of the “'''for”''' loop. |
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| | You can type the code as we go through this example. | | You can type the code as we go through this example. |
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| | Pause the tutorial while you do this. | | Pause the tutorial while you do this. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight “for”
| + | | Highlight “for” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| I have declared a “'''for”''' loop in this example.
| + | | I have declared a “'''for”''' loop in this example. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight (1..20)
| + | | Highlight (1..20) |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| We have a set of numbers 1 to 20.
| + | | We have a set of numbers 1 to 20. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight “for i in (1..20)”
| + | | Highlight “for i in (1..20)” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| We declare a variable called “'''i'''” within the “'''for”''' loop.
| + | | We declare a variable called “'''i'''” within the “'''for”''' loop. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Continue the highlight
| + | | Continue the highlight |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The variable '''“i” '''gets initialised to the first element in the set of numbers 1 to 20.
| + | | The variable '''“i” '''gets initialised to the first element in the set of numbers 1 to 20. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Continue the highlight
| + | | Continue the highlight |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight “puts”
| + | | Highlight “puts” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to the terminal and type
| + | | Switch to the terminal and type |
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| | ruby for-loop.rb | | ruby for-loop.rb |
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| | Point to the output | | Point to the output |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Now open the '''terminal''' and type
| + | | Now open the '''terminal''' and type |
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| | “'''ruby for-loop.rb'''” | | “'''ruby for-loop.rb'''” |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Analyzing the output
| + | | Analyzing the output |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The output will be an '''array''' of numbers 1 to 20.
| + | | The output will be an '''array''' of numbers 1 to 20. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| In this example, we declared a “'''for'''” loop for an inclusive range.
| + | | In this example, we declared a “'''for'''” loop for an inclusive range. |
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| | It included all numbers from 1 to 20. | | It included all numbers from 1 to 20. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch back to the same file.
| + | | Switch back to the same file. |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let's get back to the same file we were looking at.
| + | | Let's get back to the same file we were looking at. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Continue to type the next part of the code.
| + | | Continue to type the next part of the code. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight “for i in (1...20)”
| + | | Highlight “for i in (1...20)” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Continue the highlight
| + | | Continue the highlight |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Here a “'''for'''” loop is implemented for a non-inclusive range of numbers 1 to 20.
| + | | Here a “'''for'''” loop is implemented for a non-inclusive range of numbers 1 to 20. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Continue the highlight
| + | | Continue the highlight |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight the 3 dots only
| + | | Highlight the 3 dots only |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to the terminal and type
| + | | Switch to the terminal and type |
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| | ruby for-loop.rb | | ruby for-loop.rb |
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| | Point to the output | | Point to the output |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| '''No'''w open the terminal and type “'''ruby for-loop.rb'''”
| + | | '''No'''w open the terminal and type “'''ruby for-loop.rb'''” |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Analyzing the output
| + | | Analyzing the output |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| | <nowiki><Pause></nowiki> | | <nowiki><Pause></nowiki> |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Now, you should be capable enough to write your own “'''for'''” loop.
| + | | Now, you should be capable enough to write your own “'''for'''” loop. |
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| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 8
| + | | Slide 8 |
| | | | |
| | “each” loop | | “each” loop |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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”.each do |item|''' | | '''“a collection of objects”.each do |item|''' |
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Line 247: |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to gedit where you have already opened the file “each-loop.rb” with the '''each loop '''code typed inside.
| + | | Switch to gedit where you have already opened the file “each-loop.rb” with the '''each loop '''code typed inside. |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
| | | | |
| | | | |
| Line 271: |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
| + | | |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| I already have a working example of the “'''each”''' loop.
| + | | I already have a working example of the “'''each”''' loop. |
| | | | |
| | | | |
| Line 281: |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight “for”
| + | | Highlight “for” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight “for i in (1..20)”
| + | | Highlight “for i in (1..20)” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| We declare a variable called “'''i'''” within the “'''each'''” loop.
| + | | We declare a variable called “'''i'''” within the “'''each'''” loop. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Continue the highlight
| + | | Continue the highlight |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The “'''i'''” variable gets initialised to the first element in the set of numbers 1 to 20.
| + | | The “'''i'''” variable gets initialised to the first element in the set of numbers 1 to 20. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Continue the highlight
| + | | Continue the highlight |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight “puts”
| + | | Highlight “puts” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The “'''puts'''” method declared within the “'''each'''” loop is responsible for generating the output.
| + | | The “'''puts'''” method declared within the “'''each'''” loop is responsible for generating the output. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to the terminal and type “'''ruby each-loop.rb'''”
| + | | Switch to the terminal and type “'''ruby each-loop.rb'''” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Now open the '''terminal''' and type “'''ruby each-loop.rb'''”
| + | | Now open the '''terminal''' and type “'''ruby each-loop.rb'''” |
| | | | |
| | | | |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Analyzing the output
| + | | Analyzing the output |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The output will be an array of numbers 1 to 20.
| + | | The output will be an array of numbers 1 to 20. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
| + | | |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
| | | | |
| | | | |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
| + | | |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch back to gedit
| + | | Switch back to gedit |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let's get back to the same file we were looking at.
| + | | Let's get back to the same file we were looking at. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
| + | | |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Continue to type the next part of the code.
| + | | Continue to type the next part of the code. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight “for i in (1...20)”
| + | | Highlight “for i in (1...20)” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Continue the highlight
| + | | Continue the highlight |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Here a “'''each'''” loop is implemented for a non-inclusive range of numbers 1 to 20.
| + | | Here a “'''each'''” loop is implemented for a non-inclusive range of numbers 1 to 20. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Continue the highlight
| + | | Continue the highlight |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight the 3 dots only
| + | | Highlight the 3 dots only |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to the terminal and type
| + | | Switch to the terminal and type |
| | | | |
| | ruby each-loop.rb | | ruby each-loop.rb |
| Line 355: |
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| | | | |
| | Point to the output | | Point to the output |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| '''No'''w open the terminal and type “'''ruby for-loop.rb'''”
| + | | '''No'''w open the terminal and type “'''ruby for-loop.rb'''” |
| | | | |
| | | | |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
| + | | |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Now you should be capable enough to write your own “'''each'''” loop.
| + | | Now you should be capable enough to write your own “'''each'''” loop. |
| | | | |
| | <nowiki><Pause></nowiki> | | <nowiki><Pause></nowiki> |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 9
| + | | Slide 9 |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| How would we determine which looping contruct to choose?
| + | | How would we determine which looping contruct to choose? |
| | | | |
| | Let us try to recall the “'''for'''” loop construct. | | Let us try to recall the “'''for'''” loop construct. |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Open “for-loop.rb”
| + | | Open “for-loop.rb” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| In the first example, we iterated over a set of numbers 1 to 20 using “'''for'''”.
| + | | In the first example, we iterated over a set of numbers 1 to 20 using “'''for'''”. |
| | | | |
| | | | |
| Line 383: |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight “for number in (1..20)”
| + | | Highlight “for number in (1..20)” |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
| | | | |
| | | | |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|
| + | | |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
| | | | |
| | <nowiki><Pause></nowiki> | | <nowiki><Pause></nowiki> |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 10
| + | | Slide 10 |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| <nowiki><<Pause>></nowiki> | + | | <nowiki><<Pause>></nowiki> |
| | | | |
| | This brings us to the end of this Spoken Tutorial. | | This brings us to the end of this Spoken Tutorial. |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 11
| + | | Slide 11 |
| | | | |
| | Summary | | Summary |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| In this tutorial we have learnt
| + | | In this tutorial we have learnt |
| | | | |
| | * Usage of “'''for'''” loop | | * Usage of “'''for'''” loop |
| Line 413: |
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| | * 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 |
| − |
| |
| − |
| |
| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 12
| + | | Slide 12 |
| | | | |
| | Assignment | | Assignment |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| As as assignment
| + | | As as assignment |
| | | | |
| | Write a ruby program using | | Write a ruby program using |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 13
| + | | Slide 13 |
| | | | |
| | About the Spoken Tutorial Project | | About the Spoken Tutorial Project |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 14
| + | | Slide 14 |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The Spoken Tutorial Project Team :
| + | | The Spoken Tutorial Project Team : |
| | | | |
| | | | |
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| | | | |
| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 15
| + | | Slide 15 |
| | | | |
| | Acknowledgements | | Acknowledgements |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| 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. |
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| | |- | | |- |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 16
| + | | Slide 16 |
| | | | |
| | About the contributor | | About the contributor |
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| | | | |
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| * This tutorial has been contributed by Ruby Software Pvt. Ltd
| + | | * This tutorial has been contributed by Ruby Software Pvt. Ltd |
| | * http://www.ruby-software.com | | * http://www.ruby-software.com |
| | * Thank you | | * Thank you |
| − |
| |
| − |
| |
| − |
| |
| | |} | | |} |
| Visual Cue
|
Narration
|
| Slide 1
|
Welcome to the tutorial on for and each Loops in Ruby.
|
| Slide 2
|
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
|
| Slide 3
System Requirements
|
Here we are using
- Ubuntu version 12.04
- Ruby 1.9.3
|
| Slide 4
Pre-requisites
|
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.
|
| Slide 5
What is a loop?
|
A loop is a command or set of commands that are executed a fixed number of times.
|
| Slide 6
Looping statements
|
Ruby has the following main looping statements.
|
|
|
In this tutorial we will learn how to use the for and each looping constructs.
|
| Switch to gedit
|
Click on “dash-home” and type gedit to invoke the editor.
|
| Switch to terminal
|
Similarly, click on “dash-home” and select Terminal to open the terminal.
|
| Type mkdir ttt and press Enter
|
In the terminal, type “mkdir ttt”.
|
| Type cd ttt and press Enter
|
Then “cd” into that directory.
|
| Type mkdir ruby-tutorial and press Enter
|
Then type “mkdir ruby-tutorial”,
|
| Type cd ruby-tutorial and press Enter
|
And then “cd ruby-tutorial”.
|
| Type mkdir looping-statements and press Enter
|
Then type “mkdir looping-statements”
|
| Type cd looping-statements and press Enter
|
And then “cd looping-statements”
|
|
|
Now we have created the requisite folders.
Let's move ahead.
|
| Slide 7
“for” loop
|
The syntax of the “for” loop in Ruby is as follows:
for “variable” in “a collection of objects”
ruby code
end
Let us try to understand it with an example.
|
| Switch to gedit where you have already opened the file “for-loop.rb” with the for loop code typed inside.
|
Create a new file in gedit as shown in the basic level Ruby tutorials.
And name it “for-loop.rb”
|
|
|
I already have a working example of the “for” loop.
You can type the code as we go through this example.
Pause the tutorial while you do this.
|
| Highlight “for”
|
I have declared a “for” loop in this example.
|
| Highlight (1..20)
|
We have a set of numbers 1 to 20.
|
| Highlight “for i in (1..20)”
|
We declare a variable called “i” within the “for” loop.
|
| Continue the highlight
|
The variable “i” gets initialised to the first element in the set of numbers 1 to 20.
|
| Continue the highlight
|
The “for” loop declaration causes the code to iterate over each element in the set 1 to 20.
|
| Highlight “puts”
|
The “puts” method declared within the “for” loop is responsible for generating the output.
|
| Switch to the terminal and type
ruby for-loop.rb
Point to the output
|
Now open the terminal and type
“ruby for-loop.rb”
and see the output.
|
| Analyzing 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.
It included all numbers from 1 to 20.
|
|
|
Next we shall look at implementing the “for” loop for a non-inclusive range.
|
| Switch back to the same file.
|
Let's get back to the same file we were looking at.
|
|
|
Continue to type the next part of the code.
|
| Highlight “for i in (1...20)”
|
Non-inclusive means it will not include the last element in the collection of objects.
|
| Continue the highlight
|
Here a “for” loop is implemented for a non-inclusive range of numbers 1 to 20.
|
| Continue the highlight
|
You will notice shortly that the number 20 will not be printed in the output.
|
| Highlight the 3 dots only
|
The last digit does not get included when you have 3 dots between numbers.
|
| Switch to the terminal and type
ruby for-loop.rb
Point to the output
|
Now open the terminal and type “ruby for-loop.rb”
and see the output.
|
| Analyzing the output
|
The output will still be an array of numbers but will not include the number 20.
<Pause>
|
|
|
Now, you should be capable enough to write your own “for” loop.
|
| Slide 8
“each” loop
|
The syntax of the “each” loop in Ruby is as follows:
“a collection of objects”.each do |item|
ruby code
end
Let us try to understand it with an example.
|
| Switch to gedit where you have already opened the file “each-loop.rb” with the each loop code typed inside.
|
Create a new file in gedit as shown in the basic level Ruby tutorials.
And name it “each-loop.rb”
|
|
|
I already have a working example of the “each” loop.
You can type the code as we go through this example.
Pause the tutorial while you do this.
|
| Highlight “for”
|
I have declared an “each” loop in this example.
We have a set of numbers 1 to 20.
|
| Highlight “for i in (1..20)”
|
We declare a variable called “i” within the “each” loop.
|
| Continue the highlight
|
The “i” variable gets initialised to the first element in the set of numbers 1 to 20.
|
| Continue the highlight
|
The “each” loop declaration causes the code to iterate over each element in the set 1 to 20.
|
| Highlight “puts”
|
The “puts” method declared within the “each” loop is responsible for generating the output.
|
| Switch to the terminal and type “ruby each-loop.rb”
|
Now open the terminal and type “ruby each-loop.rb”
and see the output.
|
| Analyzing the output
|
The output will be an array of numbers 1 to 20.
|
|
|
In the above example we declared an “each” loop for an inclusive range.
It included all numbers from 1 to 20.
|
|
|
Next we shall look at implementing the “each” loop for a non-inclusive range.
|
| Switch back to gedit
|
Let's get back to the same file we were looking at.
|
|
|
Continue to type the next part of the code.
|
| Highlight “for i in (1...20)”
|
Non-inclusive means it will not include the last element in the collection of objects.
|
| Continue the highlight
|
Here a “each” loop is implemented for a non-inclusive range of numbers 1 to 20.
|
| Continue the highlight
|
You will notice shortly that the number 20 will not be printed in the output.
|
| Highlight the 3 dots only
|
The last digit does not get included when you have 3 dots between numbers.
|
| Switch to the terminal and type
ruby each-loop.rb
Point to the output
|
Now open the terminal and type “ruby for-loop.rb”
and see the output.
|
|
|
Now you should be capable enough to write your own “each” loop.
<Pause>
|
| Slide 9
|
How would we determine which looping contruct to choose?
Let us try to recall the “for” loop construct.
|
| Open “for-loop.rb”
|
In the first example, we iterated over a set of numbers 1 to 20 using “for”.
Execute “ruby for-loop.rb” in your terminal and see the output.
Now look at the code in gedit.
|
| Highlight “for number in (1..20)”
|
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.
|
|
|
Since the call to “for” in turn calls “each”, it is preferable to use the “each” loop instead.
<Pause>
|
| Slide 10
|
<<Pause>>
This brings us to the end of this Spoken Tutorial.
Let's summarize.
|
| Slide 11
Summary
|
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
|
| Slide 12
Assignment
|
As as assignment
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
|
| Slide 13
About the Spoken Tutorial Project
|
Watch the video available at the following link.
It summarises the Spoken Tutorial project.
If you do not have good bandwidth, you can download and watch it.
|
| Slide 14
|
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 at spoken hyphen tutorial dot org
|
| Slide 15
Acknowledgements
|
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.
More information on this Mission is available at:
spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
|
| Slide 16
About the contributor
|
* This tutorial has been contributed by Ruby Software Pvt. Ltd
|
