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Welcome to the spoken tutorial on Data Structures in Perl

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In this tutorial, we will learn about Data Structures available in Perl

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Here I am using  Ubuntu Linux12.04  operating system and Perl 5.14.2

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I will also be using the gedit Text Editor.

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You can use any text editor of your choice.

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You should have basic knowledge of Variables  in  Perl

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Knowledge of  comments, loops and conditional statements will be an added advantage.

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Please go through the relevant spoken tutorials on the spoken tutorial website.

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Perl  has 3 types of  data structure -

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Scalar

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Array

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Hash , also, called as  Associative Array

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Scalar:  This type of data structure holds a value of any data type.

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The data type can be string, number, double etc.

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It can also hold the reference to an array or reference to a hash.

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Note: Reference in Perl will be covered in subsequent tutorial.

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Scalar type of  data structure is as simple as declaring the variable.

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$count = 12 semicolon

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$string =  in single quote   'I am scalar of type string'  semicolon.

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We can perform the following operations on  scalar

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Assign a value to it

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Assign one scalar to another

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Arithmetic operations on number type of scalars like add, subtract etc

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string operations on string scalar like concatenation, substr etc

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Now let us look at an example of scalar data structure.

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Switch to terminal and type gedit scalars dot pl space & and press Enter.

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This will open the scalars dot pl file in gedit.

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Type the following code as displayed on the screen.

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This is the declaration and assignment to the scalar.

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These are few arithmetic operations that can be performed on number type of scalar

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These are string operations that can be performed on string type of scalar.

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substr is the PERL function which provides part of the string as output.

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Here index 0 specifies start of a string, i.e. from where we want to start extraction of the string.

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And 11 specify the offset upto where we want the string to be in the output.

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Press ctrl + s to save the file.

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Then switch to the terminal and execute the Perl script as

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perl scalars dot pl and press Enter

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The output shown on terminal is as highlighted

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Now, let us look at array data structure in PERL.

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Array:  It is a list of  elements.

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Elements can be string, number etc.

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It has an index, which is used for performing various operations on the array.

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Index starts with zero.

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Unlike other programming languages, there is no need to declare an array or its length before using it in Perl.

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Perl array, stretches or shrinks as per the elements added or removed from it

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The syntax to write an array is;

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at the rate variableName space equal to  space open bracket list of elements separated with comma close bracket semicolon

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Now let us look at an example of array data structure.

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Switch to terminal and type gedit perlArray dot pl space & and press Enter.

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This will open the perlArray dot pl file in gedit.

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Type the following code as displayed on the screen.

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This is the number array which has elements of number type.

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This is the string array which has elements of string type.

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This array has elements of both number and string type.

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This example shows the various types of arrays in Perl.

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This is how we can print the array in Perl.

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Press Ctrl + S to save the file.

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Then switch to  terminal and execute the Perl script as

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perl perlArray dot pl and press Enter.

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The following output is displayed on the terminal

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Now, let us look at Hash data structure in Perl.

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Hash is alternatively called as Associative array

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It is a Key Value pair data structure.

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Key in hash is unique.

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If the same key is added again, then the value of that key will be overridden by the latest value assigned to the key.

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Value can be duplicate.

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It also holds value of any data type.

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The syntax of hash is;

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percentage variable name space equal to space open bracket

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Press Enter

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single quote key Name single quote space equal to greater than sign space Value comma

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Press Enter

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single quote key Name single quote space equal to greater than sign space Value

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Press Enter

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close bracket semicolon

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Now let us look at an example of hash data structure.

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Switch to terminal and type

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gedit perlHash dot pl space & and press Enter.

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This will open the perlHash dot pl file in gedit.

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Type the following code as displayed on the screen.

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This hash indicates the marks obtained in a subject.

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This example, shows the use of hash

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Now let us see how to print the hash

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For now, just note the way I have printed the hash.

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Detailed explanation will be given in  subsequent tutorial.

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Press Ctrl + S to save the file.

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Then switch to  terminal and execute the Perl script as

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perl perlHash dot pl and press Enter.

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The following output is displayed on the terminal

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Let us summarize.

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In this tutorial, we have learnt -

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scalar

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Array and

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Hash Data Structure in Perl

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using sample programs.

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There is assignment for you -

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Declare scalar variable

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Assign value of type float to it and then print it.

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Declare and print an array of colors 'Red', 'Yellow' and 'Green'.

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Declare and print a hash of Employee Name and their department.

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Hint:  'Employee' =>(equal to greater than sign)  'John' comma

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'Department' =>(equal to greater than sign) 'Engineering'

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Watch the video available at the following link

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It summaries the Spoken Tutorial project

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If you do not have good bandwidth, you can download and watch it

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The Spoken Tutorial Project Team  Conducts workshops using spoken tutorials

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Gives certificates to those who pass an online  test

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For more details, please write to contact at spoken hyphen tutorial dot org

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Spoken Tutorial Project is a part of the Talk to a  Teacher project

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It is supported by the National Mission on Education through ICT, MHRD, Government of India.

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More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro

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Hope you enjoyed this Perl tutorial.

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This is Amol signing off.

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Thanks for joining.