PERL/C2/Conditional-statements/English-timed

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. 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, if-else
00:51	if-elsif-else and
00:53	switch .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.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 backslash 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 backslash 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 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