Difference between revisions of "PERL/C2/Conditional-statements/English-timed"

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|Welcome to the spoken tutorial on if and if-else conditional statements in Perl.

|Welcome to the spoken tutorial on if and if-else conditional statements in Perl.

   

   

|-

|-

| In this tutorial, we will learn about;  

| In this tutorial, we will learn about;  

|-

|-

|'''if ''' statement and  

|'''if ''' statement and  

|-

|-

|''' if-else''' statement in Perl  

|''' if-else''' statement in Perl  

   

   

|-

|-

| I am using '''Ubuntu Linux12.04''' operating system and '''Perl 5.14.2'''

| I am using '''Ubuntu Linux12.04''' operating system and '''Perl 5.14.2'''

   

   

|-

|-

|I will also be using the '''gedit Text Editor'''.

|I will also be using the '''gedit Text Editor'''.

    

    

|-

|-

|You can use any text editor of your choice.

|You can use any text editor of your choice.

   

   

|-

|-

| You should have basic knowledge of '''Variables '''and''' Comments '''in''' Perl.'''

| You should have basic knowledge of '''Variables '''and''' Comments '''in''' Perl.'''

   

   

|-

|-

|Knowledge of '''for''', '''foreach''' , '''while and  do-while '''loops in '''Perl''' will be an added advantage.

|Knowledge of '''for''', '''foreach''' , '''while and  do-while '''loops in '''Perl''' will be an added advantage.

|-

|-

|Please go through the relevant spoken tutorials on the spoken tutorial website.  

|Please go through the relevant spoken tutorials on the spoken tutorial website.  

   

   

|-

|-

| Perl provides the following conditional statements -  

| Perl provides the following conditional statements -  

   

   

|-

|-

|'''if'''

|'''if'''

   

   

|-

|-

|'''if-else '''

|'''if-else '''

   

   

|-

|-

|'''if-elsif-else''' and  

|'''if-elsif-else''' and  

   

   

|-

|-

|'''switch '''

|'''switch '''

   

   

|-

|-

|In this tutorial, we'll cover '''if '''and '''If-else''' statements  

|In this tutorial, we'll cover '''if '''and '''If-else''' statements  

   

   

|-

|-

|'''if'''  statement in '''Perl''' can be used  

|'''if'''  statement in '''Perl''' can be used  

   

   

|-

|-

| to execute a piece of code only when a specified condition is satisfied.  

| to execute a piece of code only when a specified condition is satisfied.  

|-

|-

|The syntax of '''if''' conditional statement is as follows  

|The syntax of '''if''' conditional statement is as follows  

   

   

|-

|-

|'''if '''space open bracket '''condition''' close bracket space Open curly bracket  

|'''if '''space open bracket '''condition''' close bracket space Open curly bracket  

   

   

|-

|-

|'''Enter'''

|'''Enter'''

   

   

|-

|-

|Piece of code semicolon,  to be executed when the condition is true   

|Piece of code semicolon,  to be executed when the condition is true   

   

   

|-

|-

| '''Enter''', Close curly bracket

| '''Enter''', Close curly bracket

   

   

|-

|-

|The code inside the '''if''' statement will be executed only when the condition is true.  

|The code inside the '''if''' statement will be executed only when the condition is true.  

   

   

|-

|-

| Now let us look at an example of '''if ''' statement.  

| Now let us look at an example of '''if ''' statement.  

   

   

|-

|-

|Open the Terminal and type  

|Open the Terminal and type  

   

   

|-

|-

|'''gedit conditionalBlocks dot pl ''' space '''&'''(ampersand )

|'''gedit conditionalBlocks dot pl ''' space '''&'''(ampersand )

   

   

|-

|-

|and press '''Enter'''

|and press '''Enter'''

   

   

|-

|-

|This will open the '''conditionalBlocks.pl''' file in gedit.  

|This will open the '''conditionalBlocks.pl''' file in gedit.  

   

   

|-

|-

|Type the following piece of code as displayed on the screen.  

|Type the following piece of code as displayed on the screen.  

   

   

|-

|-

|Here we have specified a condition for '''if''' which checks the value of variable count.  

|Here we have specified a condition for '''if''' which checks the value of variable count.  

   

   

|-

|-

| 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.  

|-

|-

|The condition '''$count equal to equal to 5 ''' is checked against the value of variable count.  

|The condition '''$count equal to equal to 5 ''' is checked against the value of variable count.  

|-

|-

|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.  

   

   

|-

|-

|Now, press '''ctrl+s''' to '''save''' the file.  

|Now, press '''ctrl+s''' to '''save''' the file.  

|-

|-

|Then switch to the terminal.  

|Then switch to the terminal.  

|-

|-

| Make sure that you are in the directory in which you have saved your file.  

| Make sure that you are in the directory in which you have saved your file.  

   

   

|-

|-

|Type the following to check for any compilation or syntax error -  

|Type the following to check for any compilation or syntax error -  

   

   

|-

|-

|'''perl hyphen c conditionalBlocks dot pl'''

|'''perl hyphen c conditionalBlocks dot pl'''

|-

|-

|  and press '''Enter. '''

|  and press '''Enter. '''

   

   

|-

|-

|The following line will be displayed on the terminal window   

|The following line will be displayed on the terminal window   

   

   

|-

|-

| '''conditionalBlocks.pl syntax OK '''

| '''conditionalBlocks.pl syntax OK '''

|-

|-

| As there is no compilation or syntax error, we will execute the Perl script by typing -  

| As there is no compilation or syntax error, we will execute the Perl script by typing -  

   

   

|-

|-

|'''perl conditionalBlocks dot pl '''

|'''perl conditionalBlocks dot pl '''

   

   

|-

|-

| and press '''Enter'''

| and press '''Enter'''

   

   

|-

|-

|The following output will be shown on terminal.  

|The following output will be shown on terminal.  

   

   

|-

|-

| ''' I am inside if statement'''

| ''' I am inside if statement'''

   

   

|-

|-

|Switch back to gedit

|Switch back to gedit

   

   

|-

|-

|Alternately, we can write the above ''' if''' statement as-  

|Alternately, we can write the above ''' if''' statement as-  

   

   

|-

|-

|'''print ''' space double quotes '''I am inside if statement''' slash '''n''' close double quotes  space '''if''' open bracket '''dollar count space equal to equal to space 5''' close bracket semicolon.

|'''print ''' space double quotes '''I am inside if statement''' slash '''n''' close double quotes  space '''if''' open bracket '''dollar count space equal to equal to space 5''' close bracket semicolon.

|-

|-

|Now, let us look at '''if-else''' statement.  

|Now, let us look at '''if-else''' statement.  

   

   

|-

|-

|This statement is used when user wants to execute  

|This statement is used when user wants to execute  

   

   

|-

|-

|one piece of code when the condition is true and  

|one piece of code when the condition is true and  

   

   

|-

|-

| another piece of code when the condition is false  

| another piece of code when the condition is false  

|-

|-

| The syntax for '''if-else''' condition is as follows -  

| The syntax for '''if-else''' condition is as follows -  

|-

|-

| '''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'''.  

   

   

|-

|-

|piece of code semicolon  

|piece of code semicolon  

|-

|-

|  to be executed when '''if''' condition is true,  

|  to be executed when '''if''' condition is true,  

   

   

|-

|-

|Press '''Enter '''

|Press '''Enter '''

|-

|-

|close curly bracket space '''else''' space open curly bracket '''Enter'''

|close curly bracket space '''else''' space open curly bracket '''Enter'''

   

   

|-

|-

| another piece of code semicolon  

| another piece of code semicolon  

   

   

|-

|-

|to be executed when if condition is false  

|to be executed when if condition is false  

|-

|-

|Press '''Enter''' close curly bracket  

|Press '''Enter''' close curly bracket  

|-

|-

| Now again, go to the '''conditionalBlocks.pl''' file which we have already created in gedit.  

| Now again, go to the '''conditionalBlocks.pl''' file which we have already created in gedit.  

   

   

|-

|-

|  Assign 4 to count variable then at the end of the if block type space  

|  Assign 4 to count variable then at the end of the if block type space  

|-

|-

|  ''' else '''

|  ''' else '''

   

   

|-

|-

| space open curly bracket press '''Enter '''

| space open curly bracket press '''Enter '''

|-

|-

|'''print''' space double quotes '''I am inside else statement slash n''' close double quotes  semicolon  

|'''print''' space double quotes '''I am inside else statement slash n''' close double quotes  semicolon  

   

   

|-

|-

|Press '''Enter''' and close  '''curly bracket.'''  

|Press '''Enter''' and close  '''curly bracket.'''  

|-

|-

|Here, '''4''' is assigned to variable '''$count.  '''

|Here, '''4''' is assigned to variable '''$count.  '''

   

   

|-

|-

|As the value of '''count''' variable does not match 5,   

|As the value of '''count''' variable does not match 5,   

|-

|-

|the code within the '''if''' block will not get execute

|the code within the '''if''' block will not get execute

   

   

|-

|-

|instead the code within the else block will get execute.

|instead the code within the else block will get execute.

   

   

|-

|-

|Now press ''' Ctrl+S''' to save the file.  

|Now press ''' Ctrl+S''' to save the file.  

   

   

|-

|-

| Now switch to terminal.  

| Now switch to terminal.  

   

   

|-

|-

|and type '''perl hyphen c conditionalBlocks dot pl''' to check for any compilation or syntax error

|and type '''perl hyphen c conditionalBlocks dot pl''' to check for any compilation or syntax error

   

   

|-

|-

|  now, press '''Enter'''

|  now, press '''Enter'''

|-

|-

| The following line will be displayed on the terminal  

| The following line will be displayed on the terminal  

   

   

|-

|-

|  '''conditionalBlocks.pl syntax OK '''

|  '''conditionalBlocks.pl syntax OK '''

|-

|-

|As there is no compilation or syntax error, we will now execute the Perl script.  

|As there is no compilation or syntax error, we will now execute the Perl script.  

   

   

|-

|-

|Type '''perl conditionalBlocks dot pl '''

|Type '''perl conditionalBlocks dot pl '''

|-

|-

| and press '''Enter'''

| and press '''Enter'''

|-

|-

| The following output will be shown on terminal.   

| The following output will be shown on terminal.   

|-

|-

|'''I am inside else statement'''

|'''I am inside else statement'''

   

   

|-

|-

|Let us summarize.   

|Let us summarize.   

   

   

|-

|-

| In this tutorial, we have learnt -  

| In this tutorial, we have learnt -  

   

   

|-

|-

|'''if''' and  

|'''if''' and  

   

   

|-

|-

|'''if-else''' conditional statements in Perl  

|'''if-else''' conditional statements in Perl  

   

   

|-

|-

|  using sample programs.  

|  using sample programs.  

|-

|-

| Here is assignment for you -   

| Here is assignment for you -   

   

   

|-

|-

|  Print ''' “It is an open source language” '''

|  Print ''' “It is an open source language” '''

|-

|-

| when the variable declared has value ''' 'Perl' '''

| when the variable declared has value ''' 'Perl' '''

|-

|-

|otherwise print ''' “It's a proprietary language” '''

|otherwise print ''' “It's a proprietary language” '''

   

   

|-

|-

|Watch the video available at the following link  

|Watch the video available at the following link  

|-

|-

|It summaries the Spoken Tutorial project

|It summaries the Spoken Tutorial project

   

   

|-

|-

|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

   

   

|-

|-

|  The Spoken Tutorial Project Team  

|  The Spoken Tutorial Project Team  

|-

|-

| Conducts workshops using spoken tutorials

| Conducts workshops using spoken tutorials

   

   

|-

|-

|Gives certificates to those who pass an online  test

|Gives certificates to those who pass an online  test

   

   

|-

|-

|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

   

   

|-

|-

|  Spoken Tutorial Project is a part of the Talk to a  Teacher project

|  Spoken Tutorial Project is a part of the Talk to a  Teacher project

   

   

|-

|-

|It is supported by the National Mission on Education through ICT, MHRD, Government of India.

|It is supported by the National Mission on Education through ICT, MHRD, Government of India.

    

    

|-

|-

|More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro

|More information on this Mission is available at spoken hyphen tutorial dot org slash NMEICT hyphen Intro

   

   

|-

|-

|  Hope you enjoyed this Perl tutorial.  

|  Hope you enjoyed this Perl tutorial.  

   

   

|-

|-

|This is Amol Brahmankar signing off.

|This is Amol Brahmankar signing off.

    

    

|-

|-

|Thanks for joining.

|Thanks for joining.

   

   

|}

|}