PERL/C2/Array-functions/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on Array Functions in PERL.
00:06	In this tutorial, we will learn about array functions in PERL like:
00:11	push , pop , shift
00:14	unshift , split
00:16	splice and join
00:18	sort, qw.
00:20	I am using Ubuntu Linux 12.04 operating system and Perl 5.14.2.
00:28	I will also be using the gedit Text Editor.
00:32	You can use any text editor of your choice.
00:36	You should have basic knowledge of variables, data Structures and arrays in PERL.
00:43	Knowledge of comments, loops and conditional statements will be an added advantage.
00:48	Please go through the relevant spoken tutorials on the spoken tutorial website.
00:54	Perl provides certain inbuilt functions.
00:57	These functions can perform various operations on an array.
01:02	Let us first learn how to add and remove elements from the last position of an array.
01:08	This can be done by using
01:10	push function which adds an element at the last position of an array
01:15	and pop function which removes an element from the last position of an array.
01:21	Let us understand push and pop functions by using a sample program.
01:26	Open the terminal and type: gedit perlArray dot pl space ampersand
01:33	and press Enter.
01:36	This will open 'perlArray dot pl' file in gedit.
01:41	Type the code as shown on the screen.
01:45	Here, we have declared an array of length 3.
01:50	push function will insert an element at the last position of this array i.e after 3
01:57	whereas pop function will remove an element from the last position of the array.
02:04	In our case, 4 will be removed from the array.
02:08	Press Ctrl + S to save the file.
02:11	push function takes 2 arguments-
02:14	1st argument to the push function is the array in which to add an element.
02:20	2nd argument is the element which is to be pushed into the array.
02:25	The syntax of pop function is as follows:
02:29	pop function takes only one argument.
02:32	It is the array from which an element needs to be removed.
02:36	Note: Both these functions work at the last position of an array.
02:41	The element removed by pop function can be collected into another variable.
02:46	The syntax for this is $variable space = space pop open bracket @myArray close bracket .
02:57	Now switch to the terminal and execute the Perl script.
03:01	Type: perl perlArray dot pl and press Enter.
03:07	The output is as shown on the terminal.
03:11	Now, let us see how to add/remove an element from the 1st position of an array.
03:18	This can be achieved using-
03:20	unshift function which adds an element to an array at the 1st position.
03:25	shift function which removes the first element from an array.
03:31	Let us understand this using a sample program.
03:35	I will open perlArray dot pl file which I have already created.
03:39	Type the following piece of code as shown on the screen.
03:43	unshift function will insert an element at the first position i.e before 1.
03:52	shift function will remove an element from the first position.
03:57	In our case, zero will be removed.
04:00	Press Ctrl + S to save the file.
04:03	The unshift function takes 2 arguments-
04:06	1st argument is the array in which to add an element,
04:10	2nd argument is the element to be added into the array .
04:15	shift function takes only one argument -
04:18	This is the array from which the element needs to be removed.
04:22	Note: Both these functions work at first position of an array.
04:27	We can collect the element removed by shift function into some variable.
04:33	The syntax for this is: $variable space = space shift open bracket @myArray close bracket.
04:44	Then switch to the terminal and execute the Perl script.
04:48	Type: perl perlArray dot pl and press Enter.
04:54	The output displayed on the terminal is as highlighted.
04:59	Now, let us see how to remove an element from a specified position of an array.
05:05	splice function removes an element from a specified position of an array.
05:11	The return value of this function is an array of removed elements.
05:17	Let us understand this using a sample program.
05:21	Go to the perlArray dot pl file which we created earlier.
05:26	Type the piece of code as shown on the screen.
05:30	We need to provide index from where we want to remove the elements and
05:35	the offset up to which we want to remove the elements.
05:39	In our case, the elements 5 and 6 will be removed.
05:44	Then switch to the terminal and execute the Perl script by typing:
05:49	perl perlArray dot pl and press Enter.
05:55	The output is as shown on the terminal.
05:59	Now, let us look at few other inbuilt functions of arrays.
06:04	split function is used to divide a string at a specified delimiter.
06:10	The return value of this function is an array.
06:14	The elements of this array are the divided portions of the string.
06:19	join function joins the elements of an array using the specified delimiter.
06:25	It returns a string of joined elements.
06:28	sort function sorts an array in alphabetical/numerical order.
06:34	qw function returns an array of words, separated by a white space.
06:40	Now, let us understand all these functions using a sample program.
06:45	Switch to terminal and type:
06:48	gedit arrayFunctions dot pl space ampersand and press Enter.
06:55	Type the following piece of code as shown on screen.
07:00	In this case, each word of the variable string will become an element of an array.
07:07	Here, each element of newArray will be joined by comma.
07:12	sort function will sort the elements of an array in alphabetical order.
07:19	qw function creates an array of words separated by space.
07:25	Let us understand each function.
07:28	split function takes two arguments.
07:31	1st argument is the delimiter by which the string needs to be split,
07:36	2nd is the string which needs to be split.
07:39	Delimiters can be specified in forward slash, single or double quotes.
07:45	join function takes 2 arguments.
07:48	1st is the delimiter by which the array elements need to be joined.
07:53	2nd is the array.
07:55	Delimiters can be specified in single or double quotes.
07:58	sort function takes a single argument which is the array that needs to be sorted.
08:05	qw function returns an array of words, separated by space.
08:11	It is not necessary to specify the word in quotes if written using qw.
08:17	Then switch to the terminal and execute the Perl script by typing:
08:23	perl arrayFunctions dot pl
08:26	and press Enter.
08:29	The following output is displayed on the screen.
08:33	Let us summarize. In this tutorial, we have learnt to:
08:36	add/remove elements from an array
08:40	basic functions which can be performed on array using sample program.
08:46	Here is an assignment for you -
08:48	'script.spoken-tutorial.org/index.php/Perl'
08:54	Split the above string at '/ ' (forward slash) delimiter.
08:59	Add https:// at the start of a newly created array.
09:06	Remove element “Perl” from the array.
09:09	Declare a number array and sort it.
09:12	Watch the video available at the following link.
09:15	It summarizes the "Spoken Tutorial" project.
09:19	If you do not have good bandwidth, you can download and watch it.
09:24	The "Spoken Tutorial" project team: Conducts workshops using spoken tutorials.
09:30	Gives certificates to those who pass an online test.
09:34	For more details, please write to: contact at spoken hyphen tutorial dot org.
09:40	"Spoken Tutorial" project is a part of the "Talk to a Teacher" project.
09:44	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
09:51	More information on this mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
10:02	Hope you enjoyed this Perl tutorial.
10:04	This is Amol, signing off.
10:06	Thanks for joining.

Contributors and Content Editors

Gaurav, PoojaMoolya, Sandhya.np14