PERL/C2/Array-functions/English-timed

Visual Cue	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
00.11	pop
00.12	shift
00.14	unshift
00.15	split
00.16	splice
00.17	and join
00.18	sort
00.19	qw
00.20	I am using Ubuntu Linux12.04 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 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 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 works at first position of an Array.
04.27	We can collect the element removed by shift function into some variable.
04.33	This 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 upto 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 needs 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.
08.34	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 programs
08.46	Here is 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 an newly created Array
09.06	Remove element “Perl” from the Array
09.09	Declare number Array and sort it
09.12	Watch the video available at the following link
09.15	It summaries 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