Difference between revisions of "PERL/C2/Conditional-statements/English-timed"
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| − | | Note the equal to equal to sign here. This is the '''comparison''' operator. | + | | Note the '''equal to equal to''' sign here. This is the '''comparison''' operator. |
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|02.23 | |02.23 | ||
| − | |When it is equal to 5, the code within the if block will get executed. | + | |When it is equal to 5, the code within the '''if''' block will get executed. |
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|03.31 | |03.31 | ||
| − | |'''print ''' space double quote '''I am inside if statement''' slash '''n''' double quote complete space '''if''' open bracket '''dollar count equal to equal to 5''' close bracket semicolon. | + | |'''print ''' space double quote '''I am inside if statement''' slash '''n''' double quote complete space '''if''' open bracket '''dollar count space equal to equal to space 5''' close bracket semicolon. |
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| 04.17 | | 04.17 | ||
| − | | '''if ''' space open bracket '''condition''' close bracket space open curly bracket Press Enter. | + | | '''if ''' space open bracket '''condition''' close bracket space open curly bracket Press '''Enter'''. |
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| 04.29 | | 04.29 | ||
| − | | to be executed when if condition is true, | + | | to be executed when '''if''' condition is true, |
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|05.30 | |05.30 | ||
| − | |Press '''Enter''' and close | + | |Press '''Enter''' and close '''curly bracket.''' |
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|05.34 | |05.34 | ||
| − | |Here, '''4''' is assigned to variable $count. | + | |Here, '''4''' is assigned to variable '''$count. ''' |
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|05.38 | |05.38 | ||
| − | |As the value of count variable does not match 5, | + | |As the value of '''count''' variable does not match 5, |
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|05.52 | |05.52 | ||
| − | |Now press Ctrl+S to save the file. | + | |Now press ''' Ctrl+S''' to save the file. |
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| 06.11 | | 06.11 | ||
| − | | | + | | now, press '''Enter''' |
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| 06.17 | | 06.17 | ||
| − | | '''conditionalBlocks.pl''' | + | | '''conditionalBlocks.pl syntax OK ''' |
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Revision as of 12:14, 28 May 2014
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| 00.01 | Welcome to the spoken tutorial on if and if-else conditional statements in Perl. |
| 00.07 | In this tutorial, we will learn about; |
| 00.09 | if statement and |
| 00.11 | if-else statement in Perl |
| 00.12 | I am using Ubuntu Linux12.04 operating system and Perl 5.14.2
|
| 00.20 | I will also be using the gedit Text Editor.
|
| 00.24 | You can use any text editor of your choice. |
| 00.28 | You should have basic knowledge of Variables and Comments in Perl.
|
| 00.33 | Knowledge of for, foreach , while and do-while loops in Perl will be an added advantage. |
| 00.40 | Please go through the relevant spoken tutorials on the spoken tutorial website. |
| 00.45 | Perl provides the following conditional statements - |
| 00.49 | if |
| 00.50 | if-else |
| 00.51 | if-elsif-else and |
| 00.53 | switch
|
| 00.54 | In this tutorial, we'll cover if and If-else statements |
| 00.59 | if statement in Perl can be used |
| 01.01 | to execute a piece of code only when a specified condition is satisfied. |
| 01.07 | The syntax of if conditional statement is as follows
|
| 01.11 | if space open bracket condition close bracket space Open curly bracket
|
| 01.19 | Enter |
| 01.20 | Piece of code semicolon, to be executed when the condition is true
|
| 01.25 | Enter, Close curly bracket
|
| 01.29 | The code inside the if statement will be executed only when the condition is true. |
| 01.36 | Now let us look at an example of if statement. |
| 01.40 | Open the Terminal and type |
| 01.43 | gedit conditionalBlocks dot pl space &(ampersand ) |
| 01.49 | and press Enter |
| 01.52 | This will open the conditionalBlocks.pl file in gedit. |
| 01.57 | Type the following piece of code as displayed on the screen. |
| 02.02 | Here we have specified a condition for if which checks the value of variable count.
|
| 02.09 | Note the equal to equal to sign here. This is the comparison operator. |
| 02.15 | The condition $count equal to equal to 5 is checked against the value of variable count.
|
| 02.23 | When it is equal to 5, the code within the if block will get executed. |
| 02.28 | Now, press ctrl+s to save the file. |
| 02.32 | Then switch to the terminal. |
| 02.36 | Make sure that you are in the directory in which you have saved your file. |
| 02.41 | Type the following to check for any compilation or syntax error - |
| 02.46 | perl hyphen c conditionalBlocks dot pl |
| 02.53 | and press Enter. |
| 02.55 | The following line will be displayed on the terminal window |
| 02.59 | conditionalBlocks.pl syntax OK
|
| 03.04 | As there is no compilation or syntax error, we will execute the Perl script by typing -
|
| 03.10 | perl conditionalBlocks dot pl |
| 03.14 | and press Enter
|
| 03.16 | The following output will be shown on terminal. |
| 03.19 | I am inside if statement |
| 03.23 | Switch back to gedit |
| 03.26 | Alternately, we can write the above if statement as- |
| 03.31 | print space double quote I am inside if statement slash n double quote complete space if open bracket dollar count space equal to equal to space 5 close bracket semicolon. |
| 03.57 | Now, let us look at if-else statement. |
| 04.01 | This statement is used when user wants to execute
|
| 04.06 | one piece of code when the condition is true and |
| 04.09 | another piece of code when the condition is false |
| 04.13 | The syntax for if-else condition is as follows - |
| 04.17 | if space open bracket condition close bracket space open curly bracket Press Enter. |
| 04.27 | piece of code semicolon |
| 04.29 | to be executed when if condition is true,
|
| 04.32 | Press Enter |
| 04.34 | close curly bracket space else space open curly bracket Enter |
| 04.41 | another piece of code semicolon
|
| 04.43 | to be executed when if condition is false |
| 04.47 | Press Enter close curly bracket |
| 04.51 | Now again, go to the conditionalBlocks.pl file which we have already created in gedit. |
| 04.58 | Assign 4 to count variable then at the end of the if block type space |
| 05.07 | else |
| 05.09 | space open curly bracket press Enter |
| 05.14 | print space double quote I am inside else statement slash n double quotes complete semicolon |
| 05.30 | Press Enter and close curly bracket. |
| 05.34 | Here, 4 is assigned to variable $count. |
| 05.38 | As the value of count variable does not match 5, |
| 05.43 | the code within the if block will not get execute |
| 05.47 | instead the code within the else block will get execute. |
| 05.52 | Now press Ctrl+S to save the file. |
| 05.56 | Now switch to terminal. |
| 05.59 | and type perl hyphen c conditionalBlocks dot pl to check for any compilation or syntax error
|
| 06.11 | now, press Enter |
| 06.13 | The following line will be displayed on the terminal |
| 06.17 | conditionalBlocks.pl syntax OK |
| 06.20 | As there is no compilation or syntax error, we will now execute the Perl script. |
| 06.27 | Type perl conditionalBlocks dot pl
|
| 06.33 | and press Enter |
| 06.35 | The following output will be shown on terminal. |
| 06.39 | I am inside else statement |
| 06.44 | Let us summarize. |
| 06.46 | In this tutorial, we have learnt - |
| 06.49 | if and |
| 06.50 | if-else conditional statements in Perl |
| 06.53 | using sample programs. |
| 06.55 | Here is assignment for you - |
| 06.57 | Print “It is an open source language” |
| 07.01 | when the variable declared has value 'Perl' |
| 07.04 | otherwise print “It's a proprietary language” |
| 07.08 | Watch the video available at the following link |
| 07.11 | It summaries the Spoken Tutorial project
|
| 07.15 | If you do not have good bandwidth, you can download and watch it |
| 07.20 | The Spoken Tutorial Project Team |
| 07.22 | Conducts workshops using spoken tutorials
|
| 07.26 | Gives certificates to those who pass an online test
|
| 07.31 | For more details, please write to contact at spoken hyphen tutorial dot org |
| 07.37 | Spoken Tutorial Project is a part of the Talk to a Teacher project
|
| 07.42 | It is supported by the National Mission on Education through ICT, MHRD, Government of India.
|
| 07.50 | More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro |
| 08.00 | Hope you enjoyed this Perl tutorial. |
| 08.04 | This is Amol Brahmankar signing off.
|
| 08.06 | Thanks for joining. |
