Difference between revisions of "PERL/C2/Data-Structures/English-timed"
From Script | Spoken-Tutorial
Sandhya.np14 (Talk | contribs) |
Sandhya.np14 (Talk | contribs) |
||
| Line 385: | Line 385: | ||
|- | |- | ||
|07:15 | |07:15 | ||
| − | | There is assignment for you - | + | | There is an assignment for you - |
|- | |- | ||
Revision as of 19:56, 3 November 2015
| 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. |
| 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. |
