Difference between revisions of "PERL/C2/Array-functions/English-timed"
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Revision as of 13:14, 28 May 2014
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| 00.01 | Welcome to the spoken tutorial on Array Functions in Perl |
| 00.06 | In this tutorial, we will learn about Array functions in Perl, like |
| 00.11 | push |
| 00.11 | pop
|
| 00.12 | shift |
| 00.14 | unshift |
| 00.15 | split |
| 00.16 | splice |
| 00.17 | and join |
| 00.18 | sort |
| 00.19 | qw |
| 00.20 | I am using Ubuntu Linux12.04 operating system and Perl 5.14.2 |
| 00.28 | I will also be using the gedit Text Editor. |
| 00.32 | You can use any text editor of your choice. |
| 00.36 | You should have basic knowledge of Variables, Data Structures and Arrays in Perl |
| 00.43 | Knowledge of Comments, 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 | Perl provides certain inbuilt functions. |
| 00.57 | These functions can perform various operations on an Array.
|
| 01.02 | Let us first learn how to add and remove elements from last position of an Array. |
| 01.08 | 'This can be done by using; |
| 01.10 | push function which adds an element at the last position of an Array |
| 01.15 | and pop function which removes an element from the last position of an Array |
| 01.21 | Let us understand push and pop functions by using a sample program. |
| 01.26 | Open the terminal and type gedit perlArray dot pl space ampersand |
| 01.33 | And Press Enter |
| 01.36 | This will open perlArray dot pl file in gedit. |
| 01.41 | Type the code as shown on the screen |
| 01.45 | Here, we have declared an Array of length 3.
|
| 01.50 | push function will insert an element at the last position of this Array i.e after 3; |
| 01.57 | whereas, pop function will remove an element from the last position of the Array.
|
| 02.04 | In our case, 4 will be removed from the Array. |
| 02.08 | Press Ctrl + S to save the file. |
| 02.11 | push function takes 2 arguments- |
| 02.14 | 1st argument to the push function, is the Array in which to add an element. |
| 02.20 | 2nd argument is the element which is to be pushed into the Array. |
| 02.25 | The syntax of pop function is as follows - |
| 02.29 | pop function takes only one argument |
| 02.32 | It is the Array from which an element needs to be removed. |
| 02.36 | Note: Both these functions work at last position of an Array.
|
| 02.41 | The element removed by pop function can be collected into another variable. |
| 02.46 | The syntax for this is $variable space = space pop open bracket @myArray close bracket
|
| 02.57 | Now switch to the terminal and execute the Perl script.
|
| 03.01 | Type perl perlArray dot pl and press Enter. |
| 03.07 | The output is as shown on the terminal.
|
| 03.11 | Now, let us see how to add/remove an element from the 1st position of an Array. |
| 03.18 | This can be achieved using-
|
| 03.20 | unshift function - which adds an element to an Array at the 1st position |
| 03.25 | shift function - which removes the first element from an Array. |
| 03.31 | Let us understand this using a sample program.
|
| 03.35 | I will open perlArray dot pl file which I have already created.
|
| 03.39 | Type the following piece of code as shown on the screen. |
| 03.43 | unshift function will insert an element at the first position i.e before 1
|
| 03.52 | shift function will remove an element from the first position. |
| 03.57 | In our case, zero will be removed. |
| 04.00 | Press Ctrl + S to save the file.
|
| 04.03 | The unshift function takes 2 arguments -
|
| 04.06 | 1st argument is the Array in which to add an element
|
| 04.10 | 2nd argument is the element to be added into the Array
|
| 04.15 | shift function takes only one argument - |
| 04.18 | This is the Array from which the element needs to be removed.
|
| 04.22 | Note: Both these functions works at first position of an Array. |
| 04.27 | We can collect the element removed by shift function into some variable. |
| 04.33 | This syntax for this is - $variable space = space shift open bracket @myArray close bracket |
| 04.44 | Then switch to the terminal and execute the Perl script. |
| 04.48 | Type perl perlArray dot pl and press Enter. |
| 04.54 | The output displayed on the terminal is as highlighted. |
| 04.59 | Now, let us see how to remove an element from a specified position of an Array. |
| 05.05 | splice function removes an element from a specified position of an Array.
|
| 05.11 | The return value of this function is an Array of removed elements.
|
| 05.17 | Let us understand this using a sample program. |
| 05.21 | Go to the perlArray dot pl file, which we created earlier. |
| 05.26 | Type the piece of code as shown on the screen.
|
| 05.30 | We need to provide index from where we want to remove the elements and |
| 05.35 | the offset upto which we want to remove the elements |
| 05.39 | In our case, the elements 5 and 6 will be removed.
|
| 05.44 | Then switch to the terminal and execute the Perl script by typing -
|
| 05.49 | perl perlArray dot pl and press Enter. |
| 05.55 | The output is as shown on the terminal
|
| 05.59 | Now let us look at few other inbuilt functions of Arrays.
|
| 06.04 | split function is used to divide a string at a specified delimiter. |
| 06.10 | The return value of this function is an Array. |
| 06.14 | The elements of this Array are the divided portions of the string. |
| 06.19 | join function joins the elements of an Array , using the specified delimiter.
|
| 06.25 | It returns a string of joined elements.
|
| 06.28 | sort function sorts an Array in alphabetical/numerical order. |
| 06.34 | qw function returns an Array of words, separated by a white space. |
| 06.40 | Now let us understand all these functions using a sample program. |
| 06.45 | Switch to terminal and type
|
| 06.48 | gedit arrayFunctions dot pl space ampersand and Press Enter |
| 06.55 | Type the following piece of code as shown on screen. |
| 07.00 | In this case, each word of the variable string will become an element of an Array |
| 07.07 | Here, each element of newArray will be joined by comma. |
| 07.12 | sort function will sort the elements of an Array in alphabetical order. |
| 07.19 | qw function creates an Array of words separated by space. |
| 07.25 | Let us understand each function. |
| 07.28 | split function takes two arguments. |
| 07.31 | 1st argument is the delimiter by which the string needs to be split |
| 07.36 | 2nd is the string which needs to be split. |
| 07.39 | Delimiters can be specified in forward slash, single or double quotes.
|
| 07.45 | join function takes 2 arguments.
|
| 07.48 | 1st is the delimiter by which the Array elements needs to be joined. |
| 07.53 | 2nd is the Array. |
| 07.55 | Delimiters can be specified in single or double quotes.
|
| 07.58 | sort function takes a single argument , which is the Array that needs to be sorted. |
| 08.05 | qw function returns an Array of words, separated by space. |
| 08.11 | It is not necessary to specify the word in quotes , if written using qw. |
| 08.17 | Then switch to the terminal and execute the Perl script by typing - |
| 08.23 | perl arrayFunctions dot pl |
| 08.26 | and press Enter. |
| 08.29 | The following output is displayed on the screen. |
| 08.33 | Let us summarize. |
| 08.34 | In this tutorial, we have learnt to -
|
| 08.36 | add/remove elements from an Array |
| 08.40 | basic functions which can be performed on Array using sample programs |
| 08.46 | Here is assignment for you - |
| 08.48 | 'script.spoken-tutorial.org/index.php/Perl' |
| 08.54 | split the above string at '/ ' (forward slash) delimiter |
| 08.59 | Add https:// at the start of an newly created Array |
| 09.06 | Remove element “Perl” from the Array |
| 09.09 | Declare number Array and sort it |
| 09.12 | Watch the video available at the following link
|
| 09.15 | It summaries the Spoken Tutorial project
|
| 09.19 | If you do not have good bandwidth, you can download and watch it |
| 09.24 | The Spoken Tutorial Project Team Conducts workshops using spoken tutorials
|
| 09.30 | Gives certificates to those who pass an online test
|
| 09.34 | For more details, please write to contact at spoken hyphen tutorial dot org |
| 09.40 | Spoken Tutorial Project is a part of the Talk to a Teacher project
|
| 09.44 | It is supported by the National Mission on Education through ICT, MHRD, Government of India.
|
| 09.51 | More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro |
| 10.02 | Hope you enjoyed this Perl tutorial. |
| 10.04 | This is Amol signing off.
|
| 10.06 | Thanks for joining. |
