PERL/C2/Data-Structures/English-timed

Time	Narration
00:00	Welcome to the spoken tutorial on Data Structures in Perl.
00:05	In this tutorial, we will learn about Data Structures available in Perl.
00:11	Here, I am using Ubuntu Linux 12.04 operating system and Perl 5.14.2.
00:18	I will also be using the gedit Text Editor.
00:22	You can use any text editor of your choice.
00:25	You should have basic knowledge of variables in Perl.
00:29	Knowledge of comments, loops and conditional statements will be an added advantage.
00:36	Please go through the relevant spoken tutorials on the Spoken Tutorial website.
00:41	Perl has 3 types of data structures:
00:44	* Scalar
00:45	* Array
00:46	* Hash, also called as Associative Array.
00:50	Scalar: This type of data structure holds a value of any data type.
00:56	The data type can be string, number, double etc.
01:01	It can also hold the reference to an array or reference to a hash.
01:06	Note: Reference in Perl will be covered in subsequent tutorial.
01:11	Scalar type of data structure is as simple as declaring the variable.
01:16	$count = 12 semicolon.
01:20	$string = in single quote 'I am scalar of type string' semicolon.
01:26	We can perform the following operations on scalar.
01:30	* Assign a value to it.
01:32	* Assign one scalar to another.
01:35	* Arithmetic operations on number type of scalars like add, subtract etc.
01:41	* String operations on string scalar like concatenation, substr etc.
01:48	Now, let us look at an example of scalar data structure.
01:52	Switch to terminal and type: gedit scalars dot pl space & (ampersand) and press Enter.
02:01	This will open the 'scalars dot pl' file in gedit.
02:05	Type the following code as displayed on the screen.
02:09	This is the declaration and assignment to the scalar.
02:13	These are few arithmetic operations that can be performed on number type of scalar.
02:19	These are the string operations that can be performed on string type of scalar.
02:25	substr is the PERL function which provides part of the string as output.
02:30	Here, index 0 (zero) specifies start of a string, i.e. from where we want to start extraction of the string.
02:39	And, 11 specifies the offset upto where we want the string to be in the output.
02:46	Press Ctrl + s to save the file.
02:50	Then switch to the terminal and execute the Perl script as:
02:55	perl scalars dot pl and press Enter.
03:00	The output shown on terminal is as highlighted.
03:05	Now, let us look at an array data structure in PERL.
03:09	Array: It is a list of elements.
03:12	Elements can be string, number etc.
03:16	It has an index which is used for performing various operations on the array.
03:22	Index starts with zero.
03:25	Unlike other programming languages, there is no need to declare an array or its length before using it in Perl.
03:33	Perl array stretches or shrinks as per the elements added or removed from it.
03:39	The syntax to write an array is:
03:41	at the rate (@) variableName space equal to space open bracket list of elements separated with comma close bracket semicolon.
03:54	Now, let us look at an example of array data structure.
03:57	Switch to terminal and type: gedit perlArray dot pl space & and press Enter.
04:08	This will open the perlArray dot pl file in gedit.
04:12	Type the following code as displayed on the screen.
04:18	This is the number array which has elements of number type.
04:23	This is the string array which has elements of string type.
04:29	This array has elements of both number and string type.
04:34	This example shows the various types of arrays in Perl.
04:39	This is how we can print the array in Perl.
04:43	Press Ctrl + S to save the file.
04:47	Then switch to terminal and execute the Perl script as:
04:52	perl perlArray dot pl and press Enter.
04:59	The following output is displayed on the terminal.
05:04	Now, let us look at Hash data structure in Perl.
05:08	Hash is alternatively called as Associative array.
05:12	It is a Key - Value pair data structure.
05:15	Key in hash is unique.
05:18	If the same key is added again, then the value of that key will be overridden by the latest value assigned to the key.
05:28	Value can be duplicate.
05:30	It also holds value of any data type.
05:34	The syntax of hash is:
05:36	percentage variable name space equal to space open bracket
05:41	Press Enter
05:42	single quote key Name single quote space equal to greater than sign space Value comma
05:50	Press Enter
05:52	single quote key Name single quote space equal to greater than sign space Value
05:58	Press Enter
06:00	close bracket semicolon.
06:03	Now let us look at an example of hash data structure.
06:07	Switch to terminal and type:
06:10	gedit perlHash dot pl space & and press Enter.
06:18	This will open the 'perlHash dot pl' file in gedit.
06:22	Type the following code as displayed on the screen.
06:27	This hash indicates the marks obtained in a subject.
06:31	This example shows the use of hash.
06:35	Now, let us see how to print the hash.
06:38	For now, just note the way I have printed the hash.
06:42	Detailed explanation will be given in subsequent tutorial.
06:47	Press Ctrl + S to save the file.
06:50	Then switch to terminal and execute the Perl script as:
06:55	perl perlHash dot pl and press Enter.
07:01	The following output is displayed on the terminal.
07:05	Let us summarize.
07:06	In this tutorial, we have learnt -
07:09	* scalar
07:10	* Array and
07:11	* Hash Data Structure in Perl,
07:13	using sample programs.
07:15	There is an assignment for you -
07:17	* Declare scalar variable
07:19	* Assign value of type float to it and then print it.
07:23	* Declare and print an array of colors 'Red', 'Yellow' and 'Green'.
07:28	* Declare and print a hash of Employee Name and their department.
07:33	Hint: 'Employee' =>(equal to greater than sign) 'John' comma
07:38	'Department' =>(equal to greater than sign) 'Engineering'.
07:42	Watch the video available at the following link.
07:46	It summarizes the Spoken Tutorial project.
07:49	If you do not have good bandwidth, you can download and watch it.
07:53	The Spoken Tutorial project team: Conducts workshops using spoken tutorials.
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08:03	For more details, please write to contact at spoken hyphen tutorial dot org.
08:10	"Spoken Tutorial" project is a part of the "Talk to a Teacher" project.
08:15	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
08:22	More information on this mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
08:33	Hope you enjoyed this Perl tutorial.
08:35	This is Amol, signing off.
08:38	Thanks for joining.

Contributors and Content Editors

Gaurav, PoojaMoolya, Sandhya.np14