PERL/C2/Arrays/English-timed

Visual Cue	Narration
00.01	Welcome to the spoken tutorial on Arrays in Perl.
00.06	In this tutorial, we will learn about
00.09	Index of an array
00.11	Length of an array
00.13	Accessing elements of an array
00.16	Looping over an array
00.18	Sequential Array
00.20	And Array Slicing
00.22	Here I am using Ubuntu Linux12.04 operating system and Perl 5.14.2
00.30	I will also be using the gedit Text Editor.
00.34	You can use any text editor of your choice.
00.37	You should have basic knowledge of Variables, Comments & Data Structures in Perl
00.43	Knowledge of 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	Array is a simple data structure which contains elements of any data type.
00.59	Array index starts from zero always.
01.03	In Perl, it is not necessary to declare the length of an array.
01.08	Array length expands/shrinks as and when elements are added/removed from it.
01.15	The syntax for declaring an array is -
01.18	@myArray equal to open bracket 1 comma 2 comma 3 comma single quote abc single quote comma 10.3 close bracket semicolon
01.31	The last index of an array can be found with this command -
01.35	$#myArray
01.38	Let us understand this using sample program.
01.42	Open the terminal and type
01.44	gedit arrayIndex dot pl space ampersand
01.50	and press Enter.
01.52	This will open arrayIndex dot pl file in geditor
01.57	Type the piece of code that is displayed on screen
02.02	Here we have declared & defined an array which contains 5 elements.
02.07	As array index starts from zero, the last index value will be 4
02.14	i.e number of elements, which is 5, minus 1.
02.18	Press Ctrl+S to save the file.
02.22	Now switch to terminal and execute the Perl script
02.26	Type - perl arrayIndex dot pl
02.30	and press Enter.
02.32	The output will be as displayed on the terminal
02.37	Now, let us see how to get length of an array in Perl.
02.41	There are many ways by which we can find the length of an array.
02.46	Index of an array + 1 i.e. $#array + 1
02.53	Using PERL inbuilt scalar function; i.e. scalar open bracket @array close bracket
03.02	Assign array to a scalar variable i.e. $arrayLength = @array
03.09	Let us look at an illustration of array length using a sample program.
03.14	Switch to the terminal and type -
03.18	gedit arrayLength dot pl space ampersand
03.24	Press Enter.
03.27	Type the following piece of code, as shown on the screen-
03.32	Here we have declared & defined an array which contains 5 elements.
03.38	So, output will display 5.
03.41	Highlighted, are various ways to find the length of an array in Perl.
03.47	Please note We have concatenated the output in the print statement using comma.
03.53	Press Ctrl + S to save the file.
03.57	Now let us execute the script.
03.59	Switch to terminal and type-
04.02	perl arrayLength dot pl and press Enter.
04.07	The output will be as displayed on the terminal.
04.12	Now, let us understand how to access individual elements in an array.
04.18	Indexing is used to access elements of an array.
04.22	Let us look at an example for accessing elements of an array at -
04.27	First Position
04.28	Last Position
04.29	Any position
04.32	Switch to the terminal and type -
04.35	gedit perlArray dot pl space ampersand
04.42	and press Enter.
04.45	Type the following piece of code as shown.
04.49	Please note-
04.50	myArray is declared with @ (at the rate) sign.
04.54	But, to access an array element we need to use $ (dollar) sign.
04.59	To access the element at any position, we need to pass index to an array
05.07	Here, to access the first element of myArray ,
05.11	zero is passed as index.
05.16	To access the last element of myArray , we have passed the last index of myArray.
05.24	Recall, we had learnt about this earlier.
05.28	Press Ctrl + S to save the file.
05.30	Switch to the terminal and execute the script as -
05.36	perl perlArray dot pl
05.41	and press Enter.
05.43	The output will be as shown on the terminal
05.47	Now, let us understand, how to loop over each element of an array.
05.52	There are two ways of looping over an array-
05.56	Using for loop
05.58	Using foreach loop
06.01	Let's learn how to use these loops to iterate over an array using a sample program.
06.07	For this, switch to the terminal and type
06.11	gedit loopingOverArray dot pl space ampersand
06.17	And Press Enter
06.20	Type the piece of code as shown on the screen
06.24	Here, we are printing each element of array by iterating the index.
06.31	The for loop will execute till the value of i variable reaches the last index of an array.
06.38	Here, foreach loop will be executed for each element of an array.
06.46	Once the array reaches its last element, it will exit the foreach loop.
06.53	Please Note: If you are not aware of for and foreach loops,
06.58	please go through the relevant spoken tutorials on spoken tutorial website.
07.04	Now, Press Ctrl + S to save the file.
07.07	Then switch to the terminal and execute the script as -
07.12	perl loopingOverArray dot pl
07.15	and press Enter.
07.19	The output will be as displayed on the terminal.
07.24	In Perl, we can declare a sequential array as-
07.28	@alphaArray = open bracket a dot dot d close bracket semicolon
07.37	i.e alphaArray will contain elements 'a', 'b', 'c' and 'd'
07.44	Similarly, @numericArray equal to open bracket 1 dot dot 5 close bracket semicolon is same as @numericArray equal to open bracket 1 comma 2 comma 3 comma 4 comma 5
08.03	Perl also provides array slicing.
08.06	This is nothing but extracting part of an array and dumping it into a new array.
08.13	@array = (19, 23, 56, 45, 87, 89 );
08.27	@newArray = @array open square bracket 1 comma 4 close square bracket semicolon
08.38	After slicing, newArray will look like
07.38	@newArray = open bracket 23 comma 87 close bracket semicolon
08.51	Let us summarize.
08.52	In this tutorial, we have learnt to-
08.55	Find index of an array
08.57	Find length of an array
08.59	Access elements of an array
09.01	Loop over an array
09.03	Sequenial Array
09.05	Array Slicing using sample programs.
09.07	Here is assignment for you -
09.10	Declare an array of rainbow colors
09.13	Print 4th element of this array
09.16	Print Length and last index of this array
09.19	Loop over each element of an array using for & foreach loops
09.25	Declare array as @myArray = (1..9); and then create an array of odd numbers from above array using array slicing.
09.41	Watch the video available at the following link
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09.48	If you do not have good bandwidth, you can download and watch it
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10.09	Spoken Tutorial Project is a part of the Talk to a Teacher project
10.13	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
10.20	More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro
10.31	Hope you enjoyed this Perl tutorial.
10.35	This is Amol signing off.
10.37	Thanks for joining.

Contributors and Content Editors

Gaurav, PoojaMoolya, Sandhya.np14