PERL/C2/Comments-in-Perl/English-timed
From Script | Spoken-Tutorial
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| 00.00 | Welcome to the spoken tutorial on Comments in Perl. |
| 00.05 | In this tutorial, we will learn about |
| 00.08 | Comments in Perl |
| 00.10 | I am using Ubuntu Linux12.04 operating system and Perl 5.14.2 |
| 00.18 | that is, Perl revision 5 version 14 and subversion 2
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| 00.23 | I will also be using the gedit Text Editor. |
| 00.27 | You can use any text editor of your choice.
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| 00.31 | You should have Basic knowledge of Compiling, Executing and Variables in Perl |
| 00.37 | If not, please go through the relevant spoken tutorials on the spoken tutorial website |
| 00.43 | Commenting a piece of code in Perl can be done in two ways: |
| 00.47 | Single Line |
| 00.48 | Multi Line |
| 00.49 | This type of comment is used when user wants to comment a single line of code or
|
| 00.55 | to add one liner text to explain the functionality of a piece of code |
| 01.01 | This type of comment starts with the symbol # (hash) . |
| 01.05 | Here is a demo. Let us open a new file in the Text Editor. |
| 01.11 | Open the Terminal and type - gedit comments dot pl space & |
| 01.19 | Once again, reminding you that the ampersand is used to free the command prompt in the terminal. And press enter |
| 01.27 | Now type the following commands. |
| 01.29 | hash Declaring count variable 'press Enter |
| 01.37 | dollar count space equal to space 1 semicolon press enter |
| 01.45 | print space double quotes Count is dollar count slash n close double quote semicolon space hash prints Count is 1 |
| 02.03 | Now Save this file by pressing ctlr S and execute the Perl script. |
| 02.08 | Switch to the Terminal, and type perl hyphen c comments dot pl and press Enter. |
| 02.18 | This tells us that there is no syntax error |
| 02.21 | Now type perl comments dot pl and press Enter. |
| 02.28 | It will show the following output - Count is 1 |
| 02.33 | Let us switch back to gedit. |
| 02.36 | In gedit, go to the first line and press enter. |
| 02.40 | Go back to the first line and type the following command. |
| 02.44 | Hash exclamation mark slash usr slash bin slash perl
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| 02.52 | This line in Perl is called as a shebang line and is the first line in a Perl program. |
| 02.59 | It tells where to find the Perl Interpreter. |
| 03.03 | Note: Though this line starts with hash symbol, it will not be considered as a single line comment by Perl. |
| 03.11 | Now let us look at multiline comments |
| 03.13 | Multi Line This type of comment is used |
| 03.17 | when user wants to comment a piece of code or to add description/usage of piece of code |
| 03.25 | This type of comment starts with the symbol equal to head and ends with equal to cut |
| 03.33 | Lets switch back to gedit and type the following in the comments dot pl file |
| 03.39 | at the end of file type equal to head, press Enter |
| 03.45 | print space double quote count variable is used for counting purpose close double quote press enter. |
| 03.59 | equal to cut |
| 04.01 | Save the file, close it and execute the Perl script. |
| 04.05 | On the Terminal, type perl hyphen c comments dot pl and press Enter. |
| 04.13 | No syntax error |
| 04.15 | so let us execute it perl comments dot pl |
| 04.21 | It will show the same output as before. Count is 1 |
| 04.27 | It does not print the sentence “count variable is used for counting purpose” |
| 04.32 | This is because we commented the portion using equal to head and equal to cut |
| 04.40 | You can either use =head =cut or =begin =end. |
| 04.48 | These are not the special keywords used by Perl. |
| 04.52 | Please note there should not be any leading or trailing space(s) before = to sign and after the head, cut, begin or end word. |
| 05.02 | Open the Terminal once again. |
| 05.05 | And Type - gedit commentsExample dot pl space & and press Enter. |
| 05.15 | Type the following commands as shown on the screen. |
| 05.19 | Here I am declaring two variables firstNum and secondNum and I am assigning some values to them. |
| 05.28 | Then I have commented this portion here. |
| 05.32 | Now I added these two numbers and assign the value to a third variable named addition. |
| 05.39 | Next I want to print the value using print command. |
| 05.44 | Save the file and execute the Perl script on the Terminal. |
| 05.49 | On terminal type perl hyphen c commentsExample dot pl, press Enter. |
| 05.57 | There is no syntax error |
| 05.59 | So execute the script by typing
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| 06.01 | perl commentsExample dot pl press enter |
| 06.07 | It will show the following output. Addition is 30 |
| 06.12 | This brings us to the end of this tutorial. |
| 06.16 | Here we learnt, To Add Comments in Perl
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| 06.19 | Write a perl script to find square of a number. |
| 06.23 | Explain the functionality of the code written using: Single Line Comment & Mutli Line Comment.
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| 06.30 | Watch the video available at the following link |
| 06.34 | It summarises the Spoken Tutorial project |
| 06.37 | If you do not have good bandwidth, you can download and watch it |
| 06.42 | The Spoken Tutorial Project Team |
| 06.44 | Conducts workshops using spoken tutorials |
| 06.48 | Gives certificates to those who pass an online test |
| 06.51 | For more details, please write to contact at spoken hyphen tutorial dot org |
| 06.58 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
| 07.03 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
| 07.11 | More information on this Mission is available at the following link. |
| 07.15 | Hope you enjoyed this Perl tutorial. This is Amol Brahmankar signing off.
Thanks for joining. |
