PERL/C2/for-for-each-loops/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on for and foreach Loops in Perl.
00:06	In this tutorial, we will learn about: for loop in Perl and
00:11	foreach loop in Perl.
00:13	I am using Ubuntu Linux 12.04 operating system and Perl 5.14.2.
00:21	I will also be using the gedit Text Editor.
00:25	You can use any text editor of your choice.
00:29	You should have basic knowledge of variables and comments in Perl.
00:33	If not, please go through the relevant spoken tutorials on the spoken tutorial website.
00:40	Perl provides a mechanism by which we can check a condition repeatedly for various values. This is done using loops.
00:49	There are various types of loops in Perl:
00:52	* for loop
00:53	* foreach loop
00:54	* while loop and
00:55	* do-while loop.
00:56	In this tutorial, we will cover for and foreach loop.
01:01	for loop in Perl can be used to execute a piece of code for a certain number of times.
01:07	The syntax of for loop is as follows:
01:10	for space open bracket variable initialization semicolon condition semicolon increment
01:20	close bracket, press Enter.
01:22	Open curly brackets,
01:24	piece of code to be executed multiple times,
01:28	close curly brackets.
01:30	Now let us look at an example of a for loop.
01:33	Open the Terminal and type: gedit forLoop.pl space & (ampersand)
01:42	and press Enter.
01:43	This will open the forLoop.pl file in gedit.
1:48	Type the following piece of code: hash exclamation mark slash u s r slash bin slash perl
01:58	press Enter.
02:00	for space open bracket dollar i equals to zero semicolon space dollar i less than or equal to four semicolon space dollar i plus plus close bracket
02:18	space
02:19	Open curly bracket press Enter.
02:21	Type: print space double quote Value of i colon <space> dollar i backslash n double quote complete semicolon
02:35	and press Enter.
02:36	Now close curly bracket.
02:39	Press Ctrl+S to save the file.
02:42	Let me explain what the for loop does.
02:46	The variable i is initialized to zero.
02:50	Next, the condition is checked.
02:53	In this case, the condition is i less than or equal to 4.
02:59	If this condition is true, the code within the curly bracket will be executed.
03:05	This means the first print statement "Value of i colon 0"
03:11	will be displayed on the terminal.
03:14	After this, the variable 'i' is incremented by 1.
03:18	And the for loop condition is checked once again.
03:23	This loop will exit when the value of ' i' becomes greater than 4.
03:29	In this case, the for loop will be executed for i = 0, 1, 2, 3, and 4.
03:38	which is a total of 5 times.
03:41	Now, switch to terminal.
03:44	Type the following to check for any compilation or syntax error:
03:48	perl hyphen c forLoop dot pl
03:54	and press Enter.
03:56	Here it displays a message:
03:58	forLoop.pl syntax OK.
04:01	So, we have no errors.
04:03	Now, let us execute the Perl script by typing perl forLoop dot pl and press Enter.
04:11	The following output will be shown on the terminal.
04:16	Now, let us look at foreach loop.
04:19	If we want to iterate a condition for an array, we can make use of foreach loop.
04:25	The syntax is: foreach space dollar variable space within brackets at the rate array space
04:35	open curly bracket
04:37	perform action on each element of an array press Enter,
04:42	close the curly bracket.
04:44	Please note: We'll cover array, array initialization and defining an array in subsequent tutorials.
04:52	Now let us look at an example of foreach loop.
04:56	Open the Terminal and type: gedit foreachLoop dot pl space ampersand and press Enter.
05:08	This will open the foreachLoop.pl file in gedit.
05:12	Type the following piece of code:
05:15	hash exclamation mark slash u s r slash bin slash perl and press Enter.
05:25	at the rate myarray space equal to space open bracket ten comma twenty comma thirty close the bracket semicolon
05:39	press Enter.
05:41	foreach space dollar var space open bracket at the rate myarray close the bracket space
05:52	open curly bracket press Enter and type:
05:56	print space double quote Element of an array is colon dollar var slash n double quote complete semicolon
06:13	press Enter and close the curly bracket.
06:17	Press Ctrl+s to save the file.
06:20	Let me explain what this code does. An array myarray is declared.
06:27	It has 3 elements 10, 20 and 30.
06:33	In each iteration of foreach loop, 'dollar var' ($var) will contain the single element of an array.
06:40	foreach keyword will repeat this loop for each element of an array.
06:47	That is, the code within the curly bracket will be executed for each myarray element.
06:55	Back-slash n (\n) will place the prompt on a new line.
07:00	This means, the first element 10 will be displayed on the terminal.
07:06	Then 20 and so on, till all the elements are printed.
07:12	This loop will exit after printing all the elements in myarray.
07:17	Now, switch to terminal and type the following to check for any compilation or syntax error.
07:24	Type: perl hyphen c foreachLoop dot pl and press Enter.
07:32	The following line will be shown on the terminal.
07:36	There are no compilation or syntax errors.
07:38	So, let us execute the Perl script.
07:41	Type: perl foreachLoop dot pl and press Enter.
07:48	The following output will be shown on the terminal.
07:54	So, that's it about for loop and foreach loop.
07:57	Let us summarize.
07:59	In this tutorial, we have learnt -
08:02	for loop and foreach loop in Perl
08:06	using some sample programs.
08:07	Here is an assignment for you -
08:10	Declare a string as 'Spoken Tutorial' and
08:13	print it 5 times.
08:16	Declare an array of colors as @colorArray = open bracket in single quote red comma white comma blue close the bracket and
08:32	print the element of an array using foreach loop.
08:36	Watch the video available at the following link.
08:40	It summarizes the Spoken Tutorial project.
08:43	If you do not have good bandwidth, you can download and watch it.
08:48	The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials.
08:55	Gives certificates to those who pass an online test.
08:59	For more details, please write to contact at spoken hyphen tutorial dot org.
09:07	"Spoken Tutorial" project is a part of the "Talk to a Teacher" project.
09:12	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
09:20	More information on this mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
09:31	Hope you enjoyed this Perl tutorial.
09:34	This is Amol, signing off.
09:36	Thanks for joining.

Contributors and Content Editors

Gaurav, Madhurig, PoojaMoolya, Sandhya.np14, Sneha