Difference between revisions of "PERL/C2/Conditional-statements/English-timed"
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− | |Welcome to the spoken tutorial on if and if-else conditional statements in Perl. | + | |Welcome to the spoken tutorial on '''if and if-else conditional statements''' in '''Perl'''. |
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| 00:07 | | 00:07 | ||
− | | In this tutorial, we will learn about | + | | In this tutorial, we will learn about: |
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|00:09 | |00:09 | ||
− | |'''if ''' statement and | + | |* '''if ''' statement and |
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|00:11 | |00:11 | ||
− | |''' if-else''' statement in Perl | + | |* ''' if-else''' statement in Perl. |
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|00:12 | |00:12 | ||
− | | I am using '''Ubuntu | + | | I am using '''Ubuntu Linux 12.04''' operating system and '''Perl 5.14.2'''. |
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| 00:28 | | 00:28 | ||
− | | You should have basic knowledge of | + | | You should have basic knowledge of variables and '''comments''' in''' Perl.''' |
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|00:33 | |00:33 | ||
− | |Knowledge of '''for''', '''foreach''' , '''while and do-while '''loops in '''Perl''' will be an added advantage. | + | |Knowledge of '''for''', '''foreach''' , '''while''' and '''do-while '''loops in '''Perl''' will be an added advantage. |
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|00:40 | |00:40 | ||
− | |Please go through the relevant spoken tutorials on the spoken tutorial website. | + | |Please go through the relevant spoken tutorials on the '''spoken tutorial''' website. |
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| 00:45 | | 00:45 | ||
− | | Perl provides the following conditional statements | + | | Perl provides the following conditional statements: |
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|00:49 | |00:49 | ||
− | |'''if''' | + | |* '''if''' |
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|00:50 | |00:50 | ||
− | |'''if-else ''' | + | |* '''if-else ''' |
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|00:51 | |00:51 | ||
− | |'''if-elsif-else''' and | + | |* '''if-elsif-else''' and |
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|00:53 | |00:53 | ||
− | |'''switch ''' | + | |* '''switch '''. |
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|00:54 | |00:54 | ||
− | |In this tutorial, we | + | |In this tutorial, we will cover '''if '''and '''if-else''' statements. |
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|01:07 | |01:07 | ||
− | |The syntax of '''if''' conditional statement is as follows | + | |The syntax of '''if''' conditional statement is as follows: |
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|05:43 | |05:43 | ||
− | |the code within the '''if''' block will not get | + | |the code within the '''if''' block will not get executed. |
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|05:47 | |05:47 | ||
− | | | + | |Instead, the code within the '''else''' block will get executed. |
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|05:52 | |05:52 | ||
− | |Now press ''' Ctrl+S''' to save the file. | + | |Now press ''' Ctrl+S''' to '''save''' the file. |
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| 05:56 | | 05:56 | ||
− | | Now switch to terminal | + | | Now switch to terminal |
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|05:59 | |05:59 | ||
− | |and type '''perl hyphen c conditionalBlocks dot pl''' to check for any compilation or syntax error | + | |and type: '''perl hyphen c conditionalBlocks dot pl''' to check for any compilation or syntax error. |
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| 06:11 | | 06:11 | ||
− | | | + | | Now, press '''Enter'''. |
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| 06:13 | | 06:13 | ||
− | | The following line will be displayed on the terminal | + | | The following line will be displayed on the terminal: |
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| 06:17 | | 06:17 | ||
− | | | + | | "conditionalBlocks.pl syntax OK" |
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|06:27 | |06:27 | ||
− | |Type '''perl conditionalBlocks dot pl ''' | + | |Type: '''perl conditionalBlocks dot pl ''' |
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| 06:33 | | 06:33 | ||
− | | and press '''Enter''' | + | | and press '''Enter'''. |
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|06:39 | |06:39 | ||
− | | | + | |"I am inside else statement". |
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| 06:46 | | 06:46 | ||
− | | In this tutorial, we have learnt | + | | In this tutorial, we have learnt: |
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| 06:53 | | 06:53 | ||
− | | | + | | using sample programs. |
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| 06:55 | | 06:55 | ||
− | | Here is assignment for you | + | | Here is an assignment for you: |
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| 06:57 | | 06:57 | ||
− | | | + | | Print “It is an open source language” |
|- | |- | ||
|07:01 | |07:01 | ||
− | | when the variable declared has value | + | | when the variable declared has value 'Perl' |
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|07:04 | |07:04 | ||
− | |otherwise print | + | |otherwise, print “It's a proprietary language”. |
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|07:08 | |07:08 | ||
− | |Watch the video available at the following link | + | |Watch the video available at the following link. |
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|07:11 | |07:11 | ||
− | |It summaries the Spoken Tutorial project | + | |It summaries the Spoken Tutorial project. |
|- | |- | ||
|07:15 | |07:15 | ||
− | |If you do not have good bandwidth, you can download and watch it | + | |If you do not have good bandwidth, you can download and watch it. |
|- | |- | ||
| 07:20 | | 07:20 | ||
− | | The Spoken Tutorial | + | | The Spoken Tutorial project Team: |
|- | |- | ||
| 07:22 | | 07:22 | ||
− | | Conducts workshops using spoken tutorials | + | | Conducts workshops using spoken tutorials. |
|- | |- | ||
|07:26 | |07:26 | ||
− | |Gives certificates to those who pass an online test | + | |Gives certificates to those who pass an online test. |
|- | |- | ||
|07:31 | |07:31 | ||
− | |For more details, please write to contact at spoken hyphen tutorial dot org | + | |For more details, please write to contact at spoken hyphen tutorial dot org. |
|- | |- | ||
| 07:37 | | 07:37 | ||
− | | Spoken Tutorial | + | | "Spoken Tutorial" project is a part of the "Talk to a Teacher" project. |
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|07:50 | |07:50 | ||
− | |More information on this | + | |More information on this mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro. |
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| 08:00 | | 08:00 | ||
− | | | + | | Hope you enjoyed this '''Perl''' tutorial. |
|- | |- | ||
|08:04 | |08:04 | ||
− | |This is Amol Brahmankar signing off. | + | |This is Amol Brahmankar, signing off. |
|- | |- |
Revision as of 09:03, 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 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 close double quotes 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 summaries 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. |