Difference between revisions of "PERL/C2/Data-Structures/English-timed"

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Revision as of 15:07, 2 June 2014

Visual Cue
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 Linux12.04 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 structure -
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 & 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 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 specifies start of a string, i.e. from where we want to start extraction of the string.


02.39 And 11 specify 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 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 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 summaries 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


07.59 Gives certificates to those who pass an online test


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