Difference between revisions of "PERL/C2/Functions-in-Perl/English-timed"
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− | |Welcome to the spoken tutorial on ''' Functions in | + | |Welcome to the spoken tutorial on ''' Functions in PERL'''. |
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| 00:06 | | 00:06 | ||
− | | In this tutorial, we will learn about | + | | In this tutorial, we will learn about: |
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|00:10 | |00:10 | ||
− | |''' | + | |* '''PERL functions''' |
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|00:11 | |00:11 | ||
− | | ''' functions''' with '''arguments ''' | + | |* '''functions''' with '''arguments''' |
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|00:13 | |00:13 | ||
− | |''' function''' with '''return values''' | + | |* ''' function''' with '''return values'''. |
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| 00:18 | | 00:18 | ||
− | | ''' Ubuntu | + | |* '''Ubuntu Linux 12.04''' operating system |
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| 00:22 | | 00:22 | ||
− | |''' Perl 5.14.2''' and | + | |* ''' Perl 5.14.2''' and |
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| 00:24 | | 00:24 | ||
− | | ''' gedit''' Text Editor | + | |* ''' gedit''' Text Editor. |
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|00:31 | |00:31 | ||
− | |You should have basic knowledge of ''' variables, comments, loops, conditional statements''' and ''' | + | |You should have basic knowledge of ''' variables, comments, loops, conditional statements''' and '''data Structures''' in PERL. |
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| 00:41 | | 00:41 | ||
− | | Please go through the relevant spoken tutorials on the ''' | + | | Please go through the relevant spoken tutorials on the '''spoken tutorial''' website. |
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|00:47 | |00:47 | ||
− | |We will first see some simple ''' | + | |We will first see some simple '''PERL functions.''' |
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|00:51 | |00:51 | ||
− | |In ''' | + | |In PERL, '''functions''', also called as ''' subroutines''', are declared with '''sub''' keyword. |
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| 00:57 | | 00:57 | ||
− | | The definition of a declared | + | | The definition of a declared function is written between curly braces. |
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|01:03 | |01:03 | ||
− | |This | + | |This function does not take any ''' arguments.''' |
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|01:07 | |01:07 | ||
− | | And, it does not return anything. | + | | And, it does not '''return''' anything. |
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|01:10 | |01:10 | ||
− | |Note: | + | |Note: function definition can be written anywhere in the script or in another '''module'''. |
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|01:17 | |01:17 | ||
− | |This ''' module''' | + | |This '''module''' must then be included in the script, to use this function. |
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|01:24 | |01:24 | ||
− | |To include the ''' module ''' file in the script, one has to use the following syntax- | + | |To include the '''module''' file in the script, one has to use the following syntax- |
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|09:22 | |09:22 | ||
− | |''' functions''' which '''return values''' using sample programs. | + | |'''functions''' which '''return values''' using sample programs. |
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|09:27 | |09:27 | ||
− | |Here is assignment for you | + | |Here is assignment for you: |
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|09:33 | |09:33 | ||
− | |Perform some action on these '''arguments ''' | + | |Perform some action on these '''arguments'''. |
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|09:43 | |09:43 | ||
− | |Watch the video available at the following link | + | |Watch the video available at the following link. |
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|09:47 | |09:47 | ||
− | |It summaries the Spoken Tutorial project | + | |It summaries the Spoken Tutorial project. |
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|09:51 | |09:51 | ||
− | |If you do not have good bandwidth, you can download and watch it | + | |If you do not have good bandwidth, you can download and watch it. |
|- | |- | ||
| 09:56 | | 09:56 | ||
− | | The Spoken Tutorial | + | | The Spoken Tutorial project team: Conducts workshops using spoken tutorials. |
|- | |- | ||
|10:02 | |10:02 | ||
− | |Gives certificates to those who pass an online | + | |Gives certificates to those who pass an online test. |
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|10:07 | |10:07 | ||
− | |For more details, please write to contact at spoken hyphen tutorial dot org | + | |For more details, please write to contact at: spoken hyphen tutorial dot org. |
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| 10:14 | | 10:14 | ||
− | | Spoken Tutorial | + | | "Spoken Tutorial" project is a part of the "Talk to a Teacher" project. |
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|10:28 | |10:28 | ||
− | |More information on this | + | |More information on this mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro. |
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| 10:40 | | 10:40 | ||
− | | | + | | Hope you enjoyed this PERL tutorial. |
|- | |- | ||
|10:43 | |10:43 | ||
− | |This is Amol signing off. | + | |This is Amol, signing off. |
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Revision as of 18:30, 13 May 2015
Time | Narration |
00:01 | Welcome to the spoken tutorial on Functions in PERL. |
00:06 | In this tutorial, we will learn about: |
00:10 | * PERL functions |
00:11 | * functions with arguments |
00:13 | * function with return values. |
00:16 | For this tutorial, I am using |
00:18 | * Ubuntu Linux 12.04 operating system |
00:22 | * Perl 5.14.2 and |
00:24 | * gedit Text Editor. |
00:27 | You can use any text editor of your choice. |
00:31 | You should have basic knowledge of variables, comments, loops, conditional statements and data Structures in PERL. |
00:41 | Please go through the relevant spoken tutorials on the spoken tutorial website. |
00:47 | We will first see some simple PERL functions. |
00:51 | In PERL, functions, also called as subroutines, are declared with sub keyword. |
00:57 | The definition of a declared function is written between curly braces. |
01:03 | This function does not take any arguments. |
01:07 | And, it does not return anything. |
01:10 | Note: function definition can be written anywhere in the script or in another module. |
01:17 | This module must then be included in the script, to use this function. |
01:24 | To include the module file in the script, one has to use the following syntax- |
01:31 | use ModuleFileName semicolon |
01:35 | Let us understand this using a sample program. |
01:39 | Open a file in your text editor and name it as simpleFunction dot pl |
01:46 | Here is my simpleFunction dot pl file in gedit. |
01:51 | Type the code as displayed on the screen. |
01:55 | Here, we are just calling a function, which we have defined. |
02:00 | Then, the execution control is passed to that function. |
02:06 | This is the declaration & definition of the function. |
02:10 | This function will print out the given text. |
02:14 | Save your file. |
02:17 | Then switch to the terminal and execute the Perl script by typing |
02:24 | perl simpleFunction dot pl |
02:28 | and press Enter. |
02:30 | The output will be as shown on the terminal |
02:38 | Now, let us see a function with arguments. |
02:44 | Let us understand this function using a sample program. |
02:48 | Open a file in your text editor and name it as functionWithArgs dot pl |
02:57 | Here is my functionWithArgs script in gedit. |
03:02 | Type the following piece of code as shown on the screen. |
03:07 | Here, we are calling a function with arguments, 10 and 20. |
03:13 | The passed arguments are caught in $var1 & $var2. |
03:20 | @_ is a special Perl variable. We will cover its details in future tutorials. |
03:29 | This function performs the addition of 2 variables and prints the answer. |
03:37 | Save your file. |
03:42 | @_ is a special Perl array. |
03:46 | This array is used to store the passed arguments. |
03:51 | Similarly, we can catch the passed arguments in variables as |
03:56 | $var1 space = space shift @_ semicolon |
04:04 | $var2 space = space shift @_ semicolon |
04:12 | shift @_ removes the element at first position from @_ array |
04:21 | and assigns it to a variable |
04:24 | Another way is; $var1 space = space dollar underscrore open square bracket zero close square bracket semicolon |
04:38 | $var2 space = space dollar underscrore open square bracket 1 close square bracket semicolon |
04:49 | The above mentioned way is similar to fetching elements of @_ array using index. |
04:59 | Now, switch to terminal and execute the script by typing - |
05:06 | perl functionWithArgs dot pl and press Enter |
05:14 | The output is as displayed on the screen |
05:23 | Now, let us look at a functions which returns a single value. |
05:32 | Let us understand the same using a sample program. |
05:35 | Let me switch to funcWithSingleRtrnVal dot pl script in gedit. |
05:46 | Open a file in your text editor and type the following piece of code as shown. |
05:52 | Here, we are calling addVariables function with parameters 10 and 20. |
06:01 | The return value of the function is caught in $addition variable. |
06:09 | This function does the addition of the passed parameters and returns the answer. |
06:15 | Save the file. |
06:17 | Now let us execute the script. |
06:20 | So, switch to terminal and type- |
06:24 | perl funcWithSingleRtrnVal dot pl and press Enter. |
06:35 | The output is as displayed on the terminal. |
06:43 | Now, let us see a function which returns multiple values. |
06:48 | Let us understand the same, using a sample program. |
06:53 | In gedit, I have opened a file and named it as funcWithMultipleRtrnVals dot pl |
07:04 | Please do like wise in your text editor |
07:08 | Now, type the following piece of code as shown. |
07:13 | Here, we are calling addVariables function with parameters 10 and 20. |
07:21 | The return values of the function are caught in variables $var1, $var2 and $addition |
07:31 | This function does the addition and returns the passed parameters and the resultant answer. |
07:42 | This illustration demonstrates how we can return an array from a function. |
07:53 | Similarly, this demonstrates how hash can be returned from a function. |
08:00 | Save your file. |
08:03 | Now let us execute the Perl script on the terminal by typing - |
08:10 | perl funcWithMultipleRtrnVals dot pl |
08:18 | and press Enter. |
08:20 | The output is as displayed on the terminal. |
08:32 | Perl provides several inbuilt functions. |
08:36 | We learnt some of them in earlier tutorials. For eg- Arrays, Hash, sort, scalar, each, keys etc. |
08:49 | Calling inbuilt functions, similar to calling any other function, which we define. |
08:57 | E.g sort open bracket @arrayName close bracket semicolon |
09:04 | Try incorporating some inbuilt functions in the sample programs we used. |
09:10 | And observe their outputs. |
09:13 | Let us summarize. |
09:15 | In this tutorial, we have learnt - |
09:17 | Functions in Perl |
09:19 | functions with arguments and |
09:22 | functions which return values using sample programs. |
09:27 | Here is assignment for you: |
09:29 | Write a function which takes 3 arguments. |
09:33 | Perform some action on these arguments. |
09:37 | Return the result of the action performed on the arguments and print the same. |
09:43 | Watch the video available at the following link. |
09:47 | It summaries the Spoken Tutorial project. |
09:51 | If you do not have good bandwidth, you can download and watch it. |
09:56 | The Spoken Tutorial project team: Conducts workshops using spoken tutorials. |
10:02 | Gives certificates to those who pass an online test. |
10:07 | For more details, please write to contact at: spoken hyphen tutorial dot org. |
10:14 | "Spoken Tutorial" project is a part of the "Talk to a Teacher" project. |
10:19 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
10:28 | More information on this mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro. |
10:40 | Hope you enjoyed this PERL tutorial. |
10:43 | This is Amol, signing off. |
10:46 | Thanks for joining. |