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PERL/C2/More-Conditional-statements/English - Revision history
2026-04-04T05:01:35Z
Revision history for this page on the wiki
MediaWiki 1.23.17
https://script.spoken-tutorial.org/index.php?title=PERL/C2/More-Conditional-statements/English&diff=11363&oldid=prev
PoojaMoolya at 07:30, 17 June 2014
2014-06-17T07:30:19Z
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<td colspan='2' style="background-color: white; color:black; text-align: center;">Revision as of 07:30, 17 June 2014</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>{| style="border-spacing:0;"</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>{| style="border-spacing:0;"</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>| style="border-top:0.05pt solid #000000;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <center>'''Visual <del class="diffchange diffchange-inline">Clue</del>'''</center></div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>| style="border-top:0.05pt solid #000000;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <center>'''Visual <ins class="diffchange diffchange-inline">Cue</ins>'''</center></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>| style="border:0.05pt solid #000000;padding:0.097cm;"| <center>'''Narration'''</center></div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>| style="border:0.05pt solid #000000;padding:0.097cm;"| <center>'''Narration'''</center></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
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PoojaMoolya
https://script.spoken-tutorial.org/index.php?title=PERL/C2/More-Conditional-statements/English&diff=5700&oldid=prev
AmolBrahmankar: Created page with ''''Title Of Script: '''if-elsif-else, switch statement '''Author:''' Amol Brahmankar '''Keywords:''' Conditional Statements in Perl, if-elsif-else, switch statement in perl vid…'
2013-08-25T07:27:08Z
<p>Created page with ''''Title Of Script: '''if-elsif-else, switch statement '''Author:''' Amol Brahmankar '''Keywords:''' Conditional Statements in Perl, if-elsif-else, switch statement in perl vid…'</p>
<p><b>New page</b></p><div>'''Title Of Script: '''if-elsif-else, switch statement<br />
<br />
'''Author:''' Amol Brahmankar<br />
<br />
'''Keywords:''' Conditional Statements in Perl, if-elsif-else, switch statement in perl video tutorial.<br />
<br />
<br />
<br />
{| style="border-spacing:0;"<br />
| style="border-top:0.05pt solid #000000;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <center>'''Visual Clue'''</center><br />
| style="border:0.05pt solid #000000;padding:0.097cm;"| <center>'''Narration'''</center><br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Welcome to the spoken tutorial on '''if-elsif-else '''and''' switch''' conditional statements in '''Perl.'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide: Learning Objectives<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| In this tutorial, we will learn about the<br />
<br />
* '''if-elsif-else '''statement and<br />
* '''switch '''statement in '''Perl'''<br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide: System Requirements<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| I am using '''Ubuntu Linux12.04''' operating system and '''Perl 5.14.2'''<br />
<br />
<br />
I will also be using the '''gedit '''Text Editor.<br />
<br />
<br />
You can use any text editor of your choice.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide: Prerequisites<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| You should have basic knowledge of '''Variables '''and''' Comments '''in''' Perl'''<br />
<br />
<br />
and knowledge of <br />
<br />
<br />
* '''for, foreach, while '''and '''do-while '''loops and<br />
* '''if '''and '''if-else''' statements <br />
<br />
will be an added advantage'''.'''<br />
<br />
<br />
Please go through relevant spoken tutorials on the '''spoken tutorial '''website.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| '''If-elsif-else '''statement in '''Perl '''can be used<br />
<br />
* to test multiple conditions and<br />
* When all conditions fail then it executes the default '''else '''block<br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide<br />
<br />
<br />
'''if (condition) {'''<br />
<br />
'''piece of code;'''<br />
<br />
'''} elsif (condition) {'''<br />
<br />
'''another piece of code;'''<br />
<br />
'''} else {'''<br />
<br />
'''code to be executed if both the above '''<br />
<br />
'''conditions are false;'''<br />
<br />
'''}'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The syntax of '''if-elsif-else '''statement''' '''is as follows <br />
<br />
<br />
'''if space '''open bracket''' condition''' close bracket '''space '''Open curly bracket <br />
<br />
Press '''Enter'''<br />
<br />
piece of code '''semicolon''' <br />
<br />
to be executed when the condition is '''true'''<br />
<br />
Press '''Enter'''<br />
<br />
<br />
Close curly bracket space '''elsif space '''open bracket '''condition '''close bracket '''space''' open curly bracket<br />
<br />
Press '''Enter'''<br />
<br />
another piece of code '''semicolon''' <br />
<br />
to be executed when '''elsif condition''' is '''true'''<br />
<br />
Press '''Enter'''<br />
<br />
close curly bracket '''space else''' '''space '''open curly bracket<br />
<br />
'''Enter'''<br />
<br />
code to be executed when both the above conditions are '''false semicolon'''<br />
<br />
Press '''Enter'''<br />
<br />
close curly bracket''' '''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide<br />
<br />
Highlight '''if (condition)'''<br />
<br />
<br />
Highlight '''elsif (condition)'''<br />
<br />
<br />
Highlight''' else'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| First, the '''if '''condition is checked and executed if the condition is '''true'''.<br />
<br />
<br />
If not, then the '''else if''' condition is checked and executed if''' '''it is '''true'''.<br />
<br />
<br />
Otherwise, the code within '''else '''block is executed.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now let us look at an example of '''if-elsif-else '''statement.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to the Terminal and type<br />
<br />
<br />
'''gedit conditionalBlocks.pl &'''<br />
<br />
<br />
and press '''Enter'''.<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Open the '''Terminal''' and type<br />
<br />
<br />
'''gedit conditionalBlocks dot pl space ampersand'''<br />
<br />
<br />
and press''' Enter'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Point to the filename '''conditionalBlocks'''.'''pl''' in the Titlebar of gedit.<br />
<br />
<br />
Type the piece of code.<br />
<br />
<br />
'''<nowiki>#!/usr/bin/perl</nowiki>'''<br />
<br />
$language = 'Perl';<br />
<br />
<br />
if ($language eq 'Perl') {<br />
<br />
print “Hi, I am Perl\n”;<br />
<br />
} elsif ($ language eq 'Java') {<br />
<br />
print “Hi, I am Java\n”;<br />
<br />
} else {<br />
<br />
print “I am not a computer language\n”;<br />
<br />
}<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| This will open the '''conditionalBlocks'''.'''pl''' file in '''gedit'''.<br />
<br />
<br />
Type the following piece of code as displayed on the screen.<br />
<br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight variables declaration<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| We have assigned the value ''''Perl'''' to variable '''language.'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight''' eq'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Note that, '''eq''' is the '''string''' '''comparison''' operator.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight the '''if-elsif-else '''code<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| And then we have the various conditons that we want to check here.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Press '''Ctrl S'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now, press '''ctrl+s''' to save the file.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to terminal<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Then switch to the '''terminal '''and execute''' '''file directly.''' '''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Type <br />
<br />
'''perl conditionalBlocks.pl'''<br />
<br />
'''Don't press Enter.'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Type, <br />
<br />
'''perl conditionalBlocks dot pl'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| '''Note: '''<br />
<br />
# I am skipping the compilation step. It is not a mandatory step for executing '''Perl''' scripts.<br />
# If there is any compilation error, <br />
<br />
* execution will throw an error and <br />
* will stop execution of script<br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Press''' Enter.'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now press''' Enter.'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight the output on the terminal<br />
<br />
<br />
Hi, I am Perl<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The output shown on the terminal is<br />
<br />
<br />
'''Hi, I am Perl '''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to '''gedit'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now, let us look at our next case.<br />
<br />
Switch to '''gedit'''.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Change '''$language = 'Java';'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Assign ''''Java'''' to variable '''language '''as shown. <br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Press '''Ctrl S'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Press '''ctrl+s''' to save the file.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to terminal<br />
<br />
<br />
'''perl conditionalBlocks.pl'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Switch to the '''terminal '''and execute''' '''the''' '''file.<br />
<br />
Type<br />
<br />
'''perl conditionalBlocks dot pl'''<br />
<br />
<br />
and press''' Enter.'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight the output on the terminal<br />
<br />
<br />
'''Hi, I am Java'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The output shown on terminal is<br />
<br />
<br />
'''Hi, I am Java '''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to '''gedit'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Again let us switch back to '''gedit'''. <br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| '''Change $language = 'English';'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now, let us assign ''''English'''' to the '''language''' variable.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Press '''Ctrl S'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Again, press '''ctrl+s''' to '''save''' the file.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to terminal<br />
<br />
<br />
'''perl conditionalBlocks.pl'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Switch to the '''terminal '''and execute''' '''the''' '''file.<br />
<br />
<br />
Type<br />
<br />
'''perl conditionalBlocks dot pl'''<br />
<br />
<br />
and press''' Enter.'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight the output on the terminal<br />
<br />
<br />
'''I am not a computer language'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The output shown on terminal is<br />
<br />
<br />
'''I am not a computer language '''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The 3 cases imply that;<br />
<br />
* Only one '''if block''' that satisfies the condition will be executed<br />
* otherwise the default''' else block''' will be executed.<br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| We can have multiple '''elsif''' conditions as per our requirement, like this.<br />
<br />
<nowiki><<Don't read out the remaining part just display>></nowiki><br />
<br />
'''if (condition) { code1; }'''<br />
<br />
'''elsif (condition) { code2; }'''<br />
<br />
'''elsif (condition) { code3; }'''<br />
<br />
'''else { default_code;}'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide: Assignment<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Here is an assignment for you -<br />
<br />
<br />
Write an '''if-elsif-else''' statement to print <br />
<br />
* “I am a Science graduate” if '''stream''' is '''science'''<br />
* “I am a Commerce graduate” if '''stream''' is '''commerce'''<br />
* “I am an Arts graduate” if '''stream''' is neither '''science '''or '''commerce'''. <br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| <nowiki><<Pause>></nowiki><br />
<br />
Now let us learn about the '''switch '''statement.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Till Perl 5.8, there was no '''switch''' statement in Perl. <br />
<br />
<br />
After that, '''Switch module''' was introduced,<br />
<br />
<br />
which provided the functionality of '''switch''' statement.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Remain on previous slide<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| '''Note:'''<br />
<br />
'''Modules''' in '''Perl''' will be covered in subsequent tutorials.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| use Switch; <br />
<br />
<br />
switch ($value) {<br />
<br />
case 1 { executes when <br />
<br />
'''$value = 1'''}<br />
<br />
case 'a' { executes when <br />
<br />
'''$value = 'a''''}<br />
<br />
else { executes when '''$value does '''<br />
<br />
'''not match any of the '''<br />
<br />
'''cases'''}<br />
<br />
}<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The syntax of '''switch '''is as follows:<br />
<br />
<br />
'''use Switch semicolon'''<br />
<br />
Press '''Enter''' <br />
<br />
'''switch''' space open bracket '''dollar value''' close bracket space open curly bracket<br />
<br />
Press '''Enter'''<br />
<br />
<br />
'''case '''space''' 1 '''space open curly bracket executes when '''dollar''' '''value '''equal to''' 1''' close curly bracket.<br />
<br />
Press '''Enter'''<br />
<br />
<br />
'''case '''space single quote''' a '''single quote space open curly bracket executes when '''dollar''' '''value '''equal to single quote '''a '''single quote''' '''close curly bracket<br />
<br />
Press '''Enter'''<br />
<br />
<br />
'''else''' space open curly bracket executes when''' dollar value '''does not match any of the cases<br />
<br />
close curly bracket<br />
<br />
Press '''Enter'''<br />
<br />
close curly bracket<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Let us understand '''switch''' using a sample program.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to the Terminal and type<br />
<br />
<br />
'''gedit sampleSwitch.pl &'''<br />
<br />
<br />
and press '''Enter'''.<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Open the '''Terminal''' and type<br />
<br />
<br />
'''gedit sampleSwitch dot pl space ampersand'''<br />
<br />
<br />
and press''' Enter'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| use Switch;<br />
<br />
$var = 'Perl'<br />
<br />
<br />
switch ($var) {<br />
<br />
case 'Perl' {print “I am Perl\n”;}<br />
<br />
case 'Java' {print “I am Java\n”;}<br />
<br />
case 'Linux' {prin “I am Linux\n”;}<br />
<br />
else {print “I am not a computer language\n”;}<br />
<br />
}<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now, type the sample program as shown on the screen.<br />
<br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Gedit<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Let us understand how the '''switch''' statement works.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''use Switch'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The '''use Switch '''statement includes the '''Switch''' module inside the '''Perl '''code.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| '''Note:''' <br />
<br />
We will learn about '''use keyword '''in detail''' '''in subsequent tutorials. <br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now we'll test the different cases.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''$var = 'Perl''''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| We have assigned ''''Perl'''' to the variable '''$var'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''switch ($var) '''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The value in variable '''$var '''is checked in the '''switch '''statement. <br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''case 'Perl' '''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| In the first case, it matches with the case ''''Perl''''.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''{print “I am Perl\n”;}'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| So the code written against this '''case''' will be executed.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Press''' ctrl+s '''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Press '''ctrl+s''' to '''save''' the file.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to '''terminal'''<br />
<br />
'''perl sampleSwitch.pl'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now, switch to '''terminal''' and execute the script<br />
<br />
<br />
'''perl sampleSwitch.pl'''<br />
<br />
press''' Enter'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| '''Terminal'''<br />
<br />
Highlight the output on '''terminal'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The following output is shown on the '''terminal'''<br />
<br />
'''I am Perl'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Switch back to '''sampleSwitch.pl''' in '''gedit'''.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Change''' $var = 'Linux''''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now, let us assign''' 'Linux' '''to the variable''' $var'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| '''Highlight switch ($var) '''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Again, the value of variable''' $var '''will be checked in '''switch. '''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''case 'Linux' '''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| It matches with the case ''''Linux''''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''{print “I am Linux\n”;}'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| So code written against this case will get executed.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to terminal<br />
<br />
'''perl sampleSwitch.pl'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now, switch to terminal and execute the script<br />
<br />
<br />
'''perl sampleSwitch.pl'''<br />
<br />
<br />
Press''' Enter'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Terminal<br />
<br />
Highlight the output on terminal<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The following output is shown on the terminal<br />
<br />
'''I am Linux'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to '''gedit'''.<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Switch to '''sampleSwitch.pl '''in '''gedit'''.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Change '''$var = '''''''Java'''' >> <br />
<br />
Highlight '''case 'Java' '''<br />
<br />
<br />
<nowiki><Don't execute this part></nowiki><br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Similarly, if variable '''$var '''has value ''''Java'''', then second case will be checked.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Change '''$var = 'English''''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now, let us assign ''''English'''' to the variable '''$var'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| '''Highlight switch ($var) '''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Again, the value of variable''' $var '''will be checked in '''switch. '''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Point to the 3 '''case '''statements >> then point to the '''else '''statement<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| It does not match any of the '''case''' statements.<br />
<br />
<br />
So the '''else''' statement will be executed.<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Switch to Highlight<br />
<br />
'''perl sampleSwitch.pl'''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now, switch to terminal and execute the script<br />
<br />
<br />
'''perl sampleSwitch.pl'''<br />
<br />
<br />
Press''' Enter'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Terminal<br />
<br />
Highlight the output on Highlight<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The following output is shown on the terminal -<br />
<br />
'''I am not a computer language'''<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The 3 '''cases''' imply that:<br />
<br />
* The value of the expression decides the '''case '''to be executed<br />
* Only the valid '''case '''will be executed and <br />
* When there is no valid '''case, '''then the default '''else case '''will be executed<br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide<br />
<br />
Highlight '''else case '''<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| It is not mandatory to write the '''else case'''. <br />
<br />
<br />
In such a scenario, <br />
<br />
* if none of the '''cases''' match <br />
* then there will be no output from the '''switch''' statement. <br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide: Assignment<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Here is another assignment for you -<br />
<br />
* Re-write the previous assignment <br />
* given earlier in this tutorial<br />
* using '''switch''' statement. <br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide: Summary<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Let us summarize.<br />
<br />
In this tutorial, we have learnt -<br />
<br />
* '''if'''-'''elsif-else''' statement and <br />
* '''switch''' statement in '''Perl'''<br />
* using sample programs.<br />
<br />
<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| About the Project<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Watch the video available at the following link<br />
<br />
<br />
It summaries the Spoken Tutorial project<br />
<br />
<br />
If you do not have good bandwidth, you can<br />
<br />
download and watch it<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Spoken Tutorial Workshops<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The Spoken Tutorial Project Team <br />
<br />
<br />
Conducts workshops using spoken tutorials<br />
<br />
<br />
Gives certificates to those who pass an online <br />
<br />
test<br />
<br />
<br />
For more details, please write to<br />
<br />
contact at spoken hyphen tutorial dot org<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Acknowledgment<br />
<br />
<br />
http://spoken-tutorial.org\NMEICT-Intro<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Spoken Tutorial Project is a part of the Talk to a <br />
<br />
Teacher project<br />
<br />
<br />
It is supported by the National Mission on<br />
<br />
Education through ICT, MHRD, Government of India.<br />
<br />
<br />
More information on this Mission is available<br />
<br />
spoken hypen tutorial dot org slash NMEICT hyphen Intro<br />
<br />
|-<br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <br />
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Hope you enjoyed this '''Perl''' tutorial. <br />
<br />
This is Amol Brahmankar signing off.<br />
<br />
<br />
Thanks for joining<br />
<br />
|}</div>
AmolBrahmankar