PERL/C2/Comments-in-Perl/English-timed

Time	Narration
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 Linux 12.04 operating system and Perl 5.14.2
00:18	that is, Perl revision 5 version 14 and subversion 2.
00:23	I will also be using the gedit Text Editor.
00:27	You can use any text editor of your choice.
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, now 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 double quotes complete semicolon space hash Prints Count is 1
02:03	Now save this file by pressing Ctrl 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
02:52	This line in Perl is called as 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	Let's 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 double quote complete 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 (equal 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
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.
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 & multiline Comment.
06:30	Watch the video available at the following link.
06:34	It summarizes 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.

Contributors and Content Editors

Gaurav, Madhurig, PoojaMoolya, Sandhya.np14, Sneha