PERL/C2/for-for-each-loops/English-timed
From Script | Spoken-Tutorial
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| 00.01 | Welcome to the spoken tutorial on for and foreach Loops in Perl
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| 00.06 | In this tutorial, we will learn about: for loop in Perl and |
| 00.11 | foreach loop in Perl
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| 00.13 | I am using Ubuntu Linux12.04 operating system and Perl 5.14.2
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| 00.21 | I will also be using the gedit Text Editor.
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| 00.25 | You can use any text editor of your choice.
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| 00.29 | You should have basic knowledge of Variables and Comments in Perl.
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| 00.33 | If not, please go through the relevant spoken tutorials on the spoken tutorial website.
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| 00.40 | Perl provides a mechanism by which we can check a condition repeatedly for various values. This is done using loops.
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| 00.49 | There are various types of loops in Perl;
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| 00.52 | for loop
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| 00.53 | foreach loop
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| 00.54 | while loop &
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| 00.55 | do-while loop
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| 00.56 | In this tutorial, we'll cover for and foreach loop.
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| 01.01 | for loop in Perl can be used to execute a piece of code for a certain number of times.
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| 01.07 | The syntax of for loop is as follows: |
| 01.10 | for space open bracket variable initialization semicolon condition semicolon increment |
| 01.20 | close bracket Press Enter
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| 01.22 | Open curly brackets
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| 01.24 | Piece of code to be executed multiple times
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| 01.28 | Close curly brackets
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| 01.30 | Now let us look at an example of a for loop.
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| 01.33 | Open the Terminal and type; gedit forLoop.pl space & (ampersand)
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| 01.42 | and press Enter
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| 01.43 | This will open the forLoop.pl file in gedit.
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| 1.48 | Type the following piece of code;hash exclamation mark slash u s r slash bin slash perl
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| 01.58 | Press Enter
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| 02.00 | for space open bracket dollar i equals to zero semicolon space dollar i less than or equal to four semicolon space dollar i plus plus close bracket
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| 02.18 | space
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| 02.19 | Open curly bracket press enter
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| 02.21 | typeprint space double quote Value of i colon space dollar I slash n double quote complete semicolon
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| 02.35 | And Press Enter now
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| 02.36 | And Close curly bracket
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| 02.39 | Press Ctrl+S to save the file.
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| 02.42 | Let me explain what the for loop does. |
| 02.46 | The variable i is initialized to zero.
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| 02.50 | Next, the condition is checked.
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| 02.53 | In this case, the condition is i is less than or equal to 4.
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| 02.59 | If this condition is true, the code within the curly bracket will be executed.
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| 03.06 | This means the first print statement "Value of i: 0"
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| 03.11 | will be displayed on the terminal.
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| 03.14 | After this, the variable i is incremented by 1.
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| 03.19 | And the for loop condition is checked once again.
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| 03.23 | This loop will exit when the value of i becomes greater than 4.
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| 03.29 | In this case, the for loop will be executed for i = 0, 1, 2, 3, 4
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| 03.38 | which is a total of 5 times.
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| 03.41 | Now, switch to the terminal.
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| 03.44 | Type the following to check for any compilation or syntax error:
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| 03.49 | perl hyphen c forLoop dot pl
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| 03.54 | and press Enter.
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| 03.56 | Here it displays a message
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| 03.58 | forLoop.pl syntax OK
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| 04.01 | So, we have no errors.
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| 04.03 | Now, let's execute the Perl script by typing perl forLoop dot pl and press Enter.
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| 04.12 | The following output will be shown on terminal.
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| 04.16 | Now, let us look at the foreach loop.
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| 04.19 | If we want to iterate a condition for an array, we can make use of foreach loop.
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| 04.25 | The syntax is: foreach space dollar variable space within brackets at the rate array
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| 04.34 | space
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| 04.35 | open curly bracket
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| 04.37 | perform action on each element of an array Press Enter
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| 04.42 | Close the curly bracket.
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| 04.44 | Please note: We'll cover array, array initialization and defining an array in subsequent tutorials.
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| 04.53 | Now let us look at an example of foreach loop.
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| 04.57 | Open the Terminal and type gedit foreachLoop dot pl space ampersandand Press Enter
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| 05.08 | This will open the foreachLoop.pl file in gedit.
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| 05.10 | Type the following piece of code |
| 05.15 | hash exclamation mark slash u s r slash bin slash perl and Press Enter
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| 05.25 | at the rate myarray is equal to open bracket ten comma space twenty comma space thirty close bracket semicolon
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| 05.39 | press enter
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| 05.41 | foreach space dollar var space open bracket at the rate myarray close bracket space |
| 05.52 | Open curly bracket press enter and type
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| 05.56 | print space double quote Element of array is colon dollar var space slash n double quote complete semicolon
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| 06.13 | Press Enter and Close curly bracket
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| 06.17 | Press ctrl+s to save the file.
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| 06.21 | Let me explain what this code does. An array myarray is declared.
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| 06.28 | It has 3 elements 10, 20 and 30.
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| 06 .33 | In each iteration of foreach loop dollar var will contain the single element of an array
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| 06.41 | foreach keyword will repeat this loop for each element of an array.
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| 06.48 | That is, the code within the curly bracket will be executed for each myarray element.
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| 06.56 | Back-slash n will place the prompt on a new line.
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| 07.01 | This means the first element '10' will be displayed on the terminal. |
| 07.07 | Then 20 and so on, till all the elements are printed.
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| 07.12 | This loop will exit after printing all the elements in myarray.
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| 07.17 | Now, switch to terminal and type the following to check for any compilation or syntax error.
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| 07.24 | type perl hyphen c foreachLoop dot pland press Enter.
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| 07.32 | The following line will be shown on terminal
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| 07.36 | There are no compilation or syntax errors.
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| 07.39 | So let us execute the Perl script.
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| 07.41 | Type perl foreachLoop dot pl and press Enter
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| 07.49 | The following output will be shown on terminal. |
| 07.54 | So, that's it about for loop and foreach loop.
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| 07.57 | Let us summarize.
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| 07.59 | In this tutorial, we have learnt -
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| 08.03 | for loop and foreach loop in Perl
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| 08.06 | using some sample programs.
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| 08.08 | Here is an assignment for you -
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| 08.10 | Declare a string as 'Spoken Tutorial' and |
| 08.14 | Print it 5 times |
| 08.16 | Declare an array of colours as @colorArray = ('red', 'white', 'blue') and |
| 08.32 | Print the element of an array using foreach loop
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| 08.36 | Watch the video available at the following link
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| 08.40 | It summaries the Spoken Tutorial project
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| 08.44 | If you do not have good bandwidth, you can download and watch it
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| 08.49 | The Spoken Tutorial Project Team Conducts workshops using spoken tutorials
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| 08.55 | Gives certificates to those who pass an online test
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| 09.00 | For more details, please write to contact at spoken hyphen tutorial dot org
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| 09.08 | Spoken Tutorial Project is a part of the Talk to a Teacher project
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| 09.12 | It is supported by the National Mission on Education through ICT, MHRD, Government of India.
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| 09.20 | More information on this Mission is available spoken hypen tutorial dot org slash NMEICT hyphen Intro
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| 09.31 | Hope you enjoyed this Perl tutorial.
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| 09.34 | This is Amol Brahmankar signing off.
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| 09.36 | Thanks for joining.
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