Difference between revisions of "PERL/C2/Conditional-statements/English-timed"

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|Please go through the relevant spoken tutorials on the '''spoken tutorial''' website.  
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|Please go through the relevant spoken tutorials on the '''Spoken Tutorial''' website.  
 
   
 
   
 
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|'''if '''space open bracket '''condition''' close bracket space Open curly bracket  
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|'''if''' space open bracket '''condition''' close bracket space open curly bracket  
 
   
 
   
 
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|01:20
 
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|Piece of code semicolon,  to be executed when the condition is true   
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|piece of code semicolon to be executed when the condition is true   
 
   
 
   
 
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|01:25
 
|01:25
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| '''Enter''', Close curly bracket
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| '''Enter''' close curly bracket.
 
   
 
   
 
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|01:29
 
|01:29
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|The code inside the '''if''' statement will be executed only when the condition is true.  
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|The code inside the '''if''' statement will be executed only when the '''condition''' is true.  
 
   
 
   
 
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|Open the Terminal and type  
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|Open the Terminal and type:
 
   
 
   
 
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|01:43
 
|01:43
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|'''gedit conditionalBlocks dot pl ''' space '''&'''(ampersand )
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|'''gedit conditionalBlocks dot pl''' space '''&'''(ampersand )
 
   
 
   
 
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|01:49
 
|01:49
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|and press '''Enter'''
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|and press '''Enter'''.
 
   
 
   
 
|-
 
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|01:52
 
|01:52
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|This will open the '''conditionalBlocks.pl''' file in gedit.  
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|This will open the '''conditionalBlocks.pl''' file in '''gedit'''.  
 
   
 
   
 
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|02:02
 
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|Here we have specified a condition for '''if''' which checks the value of variable count.  
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|Here we have specified a condition for '''if''' which checks the value of variable '''count'''.  
 
   
 
   
 
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|02:09
 
|02:09
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| Note the '''equal to equal to''' sign here. This is the '''comparison''' operator.  
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| Note the '''equal to equal to''' sign here. This is the comparison operator.  
  
 
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|02:15
 
|02:15
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|The condition '''$count equal to equal to 5 ''' is checked against the value of variable count.  
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|The condition '''$count equal to equal to 5 ''' is checked against the value of variable '''count'''.  
  
 
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|Type the following to check for any compilation or syntax error -
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|Type the following to check for any compilation or syntax error: 
 
   
 
   
 
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|The following line will be displayed on the terminal window   
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|The following line will be displayed on the terminal window:  
 
   
 
   
 
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|  02:59
 
|  02:59
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| '''conditionalBlocks.pl syntax OK '''
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| "conditionalBlocks.pl syntax OK".
  
 
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|  03:04
 
|  03:04
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| As there is no compilation or syntax error, we will execute the Perl script by typing -
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| As there is no compilation or syntax error, we will execute the Perl script by typing:
 
   
 
   
 
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| and press '''Enter'''
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| and press '''Enter'''.
 
   
 
   
 
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| ''' I am inside if statement'''
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| "I am inside if statement".
 
   
 
   
 
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| 03:23
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|Switch back to gedit
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|Switch back to '''gedit'''.
 
   
 
   
 
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|03:26
 
|03:26
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|Alternately, we can write the above ''' if''' statement as-
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|Alternately, we can write the above ''' if''' statement as:
 
   
 
   
 
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|03:31
 
|03:31
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|'''print ''' space double quotes '''I am inside if statement''' slash '''n''' close double quotes space '''if''' open bracket '''dollar count space equal to equal to space 5''' close bracket semicolon.
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|'''print''' space double quotes '''I am inside if statement''' slash '''n''' close double quotes space '''if''' space open bracket '''dollar count space equal to equal to space 5''' close bracket semicolon.
  
 
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|one piece of code when the condition is true and  
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|one piece of code when the condition is '''true''' and  
 
   
 
   
 
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|  04:09
 
|  04:09
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| another piece of code when the condition is false  
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| another piece of code when the condition is '''false'''.
  
 
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|  04:13
 
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| The syntax for '''if-else''' condition is as follows -
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| The syntax for '''if-else''' condition is as follows:
  
 
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|  to be executed when '''if''' condition is true,  
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|  to be executed when '''if''' condition is '''true''',  
 
   
 
   
 
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|Press '''Enter '''
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|press '''Enter '''
  
 
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|to be executed when if condition is false  
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|to be executed when '''if''' condition is '''false'''
  
 
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|Press '''Enter''' close curly bracket  
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|press '''Enter''' close curly bracket.
  
 
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|04:51
 
|04:51
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| Now again, go to the '''conditionalBlocks.pl''' file which we have already created in gedit.  
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| Now, again go to the '''conditionalBlocks.pl''' file which we have already created in '''gedit'''.  
 
   
 
   
 
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| 04:58
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|  Assign 4 to count variable then at the end of the if block type space  
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|  Assign 4 to '''count''' variable. Then at the end of the '''if''' block, type: space  
  
 
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|'''print''' space double quotes '''I am inside else statement slash n''' close double quotes semicolon  
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|'''print''' space double quotes '''I am inside else statement slash n''' double quotes complete semicolon  
 
   
 
   
 
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|05:30
 
|05:30
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|Press '''Enter''' and close '''curly bracket.'''
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|Press '''Enter''' and close curly bracket.  
  
 
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|05:34
 
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|Here, '''4''' is assigned to variable '''$count. '''
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|Here, 4 is assigned to variable '''$count.'''
 
   
 
   
 
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|As there is no compilation or syntax error, we will now execute the Perl script.  
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|As there is no compilation or syntax error, we will now execute the '''Perl script'''.  
 
   
 
   
 
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| Print “It is an open source language”
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| Print “It is an open source language”
  
 
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|It summaries the Spoken Tutorial project.
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|It summarizes the Spoken Tutorial project.
 
   
 
   
 
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|-

Revision as of 09:57, 8 May 2015

Time Narration
00:01 Welcome to the spoken tutorial on if and if-else conditional statements in Perl.
00:07 In this tutorial, we will learn about:
00:09 * if statement and
00:11 * if-else statement in Perl.
00:12 I am using Ubuntu Linux 12.04 operating system and Perl 5.14.2.
00:20 I will also be using the gedit Text Editor.
00:24 You can use any text editor of your choice.
00:28 You should have basic knowledge of variables and comments in Perl.
00:33 Knowledge of for, foreach , while and do-while loops in Perl will be an added advantage.
00:40 Please go through the relevant spoken tutorials on the Spoken Tutorial website.
00:45 Perl provides the following conditional statements:
00:49 * if
00:50 * if-else
00:51 * if-elsif-else and
00:53 * switch .
00:54 In this tutorial, we will cover if and if-else statements.
00:59 if statement in Perl can be used
01:01 to execute a piece of code only when a specified condition is satisfied.
01:07 The syntax of if conditional statement is as follows:
01:11 if space open bracket condition close bracket space open curly bracket
01:19 Enter
01:20 piece of code semicolon to be executed when the condition is true
01:25 Enter close curly bracket.
01:29 The code inside the if statement will be executed only when the condition is true.
01:36 Now let us look at an example of if statement.
01:40 Open the Terminal and type:
01:43 gedit conditionalBlocks dot pl space &(ampersand )
01:49 and press Enter.
01:52 This will open the conditionalBlocks.pl file in gedit.
01:57 Type the following piece of code as displayed on the screen.
02:02 Here we have specified a condition for if which checks the value of variable count.
02:09 Note the equal to equal to sign here. This is the comparison operator.
02:15 The condition $count equal to equal to 5 is checked against the value of variable count.
02:23 When it is equal to 5, the code within the if block will get executed.
02:28 Now, press ctrl+s to save the file.
02:32 Then switch to the terminal.
02:36 Make sure that you are in the directory in which you have saved your file.
02:41 Type the following to check for any compilation or syntax error:
02:46 perl hyphen c conditionalBlocks dot pl
02:53 and press Enter.
02:55 The following line will be displayed on the terminal window:
02:59 "conditionalBlocks.pl syntax OK".
03:04 As there is no compilation or syntax error, we will execute the Perl script by typing:
03:10 perl conditionalBlocks dot pl
03:14 and press Enter.
03:16 The following output will be shown on terminal.
03:19 "I am inside if statement".
03:23 Switch back to gedit.
03:26 Alternately, we can write the above if statement as:
03:31 print space double quotes I am inside if statement slash n close double quotes space if space open bracket dollar count space equal to equal to space 5 close bracket semicolon.
03:57 Now, let us look at if-else statement.
04:01 This statement is used when user wants to execute
04:06 one piece of code when the condition is true and
04:09 another piece of code when the condition is false.
04:13 The syntax for if-else condition is as follows:
04:17 if space open bracket condition close bracket space open curly bracket Press Enter.
04:27 piece of code semicolon
04:29 to be executed when if condition is true,
04:32 press Enter
04:34 close curly bracket space else space open curly bracket Enter
04:41 another piece of code semicolon
04:43 to be executed when if condition is false
04:47 press Enter close curly bracket.
04:51 Now, again go to the conditionalBlocks.pl file which we have already created in gedit.
04:58 Assign 4 to count variable. Then at the end of the if block, type: space
05:07 else
05:09 space open curly bracket press Enter
05:14 print space double quotes I am inside else statement slash n double quotes complete semicolon
05:30 Press Enter and close curly bracket.
05:34 Here, 4 is assigned to variable $count.
05:38 As the value of count variable does not match 5,
05:43 the code within the if block will not get executed.
05:47 Instead, the code within the else block will get executed.
05:52 Now press Ctrl+S to save the file.
05:56 Now switch to terminal
05:59 and type: perl hyphen c conditionalBlocks dot pl to check for any compilation or syntax error.
06:11 Now, press Enter.
06:13 The following line will be displayed on the terminal:
06:17 "conditionalBlocks.pl syntax OK"
06:20 As there is no compilation or syntax error, we will now execute the Perl script.
06:27 Type: perl conditionalBlocks dot pl
06:33 and press Enter.
06:35 The following output will be shown on terminal.
06:39 "I am inside else statement".
06:44 Let us summarize.
06:46 In this tutorial, we have learnt:
06:49 if and
06:50 if-else conditional statements in Perl
06:53 using sample programs.
06:55 Here is an assignment for you:
06:57 Print “It is an open source language”
07:01 when the variable declared has value 'Perl'
07:04 otherwise, print “It's a proprietary language”.
07:08 Watch the video available at the following link.
07:11 It summarizes the Spoken Tutorial project.
07:15 If you do not have good bandwidth, you can download and watch it.
07:20 The Spoken Tutorial project Team:
07:22 Conducts workshops using spoken tutorials.
07:26 Gives certificates to those who pass an online test.
07:31 For more details, please write to contact at spoken hyphen tutorial dot org.
07:37 "Spoken Tutorial" project is a part of the "Talk to a Teacher" project.
07:42 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
07:50 More information on this mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
08:00 Hope you enjoyed this Perl tutorial.
08:04 This is Amol Brahmankar, signing off.
08:06 Thanks for joining.

Contributors and Content Editors

Gaurav, PoojaMoolya, Sandhya.np14

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