Difference between revisions of "PERL/C2/Conditional-statements/English-timed"
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Revision as of 11:52, 8 May 2014
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| 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 Linux12.04 operating system and Perl 5.14.2
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| 00.20 | I will also be using the gedit Text Editor.
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| 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'll 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
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| 01.11 | if space open bracket condition close bracket space Open curly bracket
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| 01.19 | Enter |
| 01.20 | Piece of code semicolon, to be executed when the condition is true
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| 01.25 | Enter, Close curly bracket
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| 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.
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| 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.
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| 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 -
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| 03.10 | perl conditionalBlocks dot pl |
| 03.14 | and press Enter
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| 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 quote I am inside if statement slash n double quote complete space if open bracket dollar count equal to equal to 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
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| 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,
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| 04.32 | Press Enter |
| 04.34 | close curly bracket space else space open curly bracket Enter |
| 04.41 | another piece of code semicolon
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| 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 quote I am inside else statement slash n double quotes complete semicolon |
| 05.30 | Press Enter and close the 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 execute |
| 05.47 | instead the code within the else block will get execute. |
| 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
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| 06.11 | and 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
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| 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 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. |
