Difference between revisions of "PERL/C2/Variables-in-Perl/English-timed"

| Welcome to the spoken tutorial on Variables in '''Perl'''.  

|  In this tutorial, we will learn about Variables in '''Perl'''

| '''Perl''' '''5.14.2 ''' that is, '''Perl''' revision 5 version 14 and subversion 2

 

| '''Variables''' are used for storing values, like text strings, numbers or arrays.

| Once a '''variable''' is declared, it can be used over and over again in the script.

| '''Scalar variables''' are declared using $ ('''dollar''') symbol.

|  Let us look at '''Variable Declaration''':

| A '''variable''' can be declared as follows: '''dollar priority semicolon'''

 

| '''Variable''' names in '''Perl''' can have several formats. '''Variables''' must begin with a letter or '''underscore'''  

|  And may contains letters, digits, '''underscores''' or a combination of above 3.

|  '''Variables''' declared with CAPITAL letters have special meaning in '''Perl.'''  

| So avoid declaring '''variables''' using Capital letters.

|  Now open the '''Terminal''' and type  '''gedit variables dot pl ampersand '''

 

| The '''ampersand''' will unlock the command prompt on the '''terminal'''. Now press '''Enter'''.

|  This will open the '''variables.pl '''file in '''gedit''' text editor.

| '''dot pl '''is the default extension of a '''Perl''' file.

|  Type the following in the file; '''dollar priority semicolon''' and press '''Enter'''.

| You do not need to declare a '''variable''' before using it;

|  Now let us assign a numerical value to the '''variable priority'''.  

| For this type '''dollar priority space equal to space one semicolon'''

|  Next, type

| '''print space double quote Value of variable is: dollar priority slash n''' close double quote '''semicolon''' and press enter

| '''slash n''' is the new line character.

|  Now save this file as '''variables.pl''' at any location.

| In my case, it will get saved in '''home/amol '''directory. Now save this file

|  Now, let us change the permissions of '''variables.pl''' file, which we just now created.

| This will provide read, write & execute rights to the file.

|  To compile this '''Perl''' script, on the '''Terminal'''

| type ;'''perl hyphen c variables dot pl'''

| Now press '''Enter'''

|  Now let's execute the '''Perl''' script by typing '''perl variables dot pl''' and press '''Enter'''.

|  Instead of '''dollar priority equal to one;''' type

| '''dollar priority equal to in single quote high '''

| A '''scalar''' can hold data of any type, be it a '''string''', a number  

|  Save this file and compile the script once again by typing

 

| Execute the script by typing '''perl variables dot pl''' and press '''Enter'''.

|  The output is as shown.

|  Now switch back to the Text Editor window.

 

| You can also use '''scalars''' within a double-quoted '''strings''' as

| '''dollar priority in double quote String'''

 

| Save this file and close it.

|  let us learn how to declare multiple '''variables'''.

| To do so open the new file in Text Editor.

|  on'''Terminal''' type - '''gedit multivar dot pl space ampersand''' and press '''Enter'''.

 

| This will open '''multivar dot pl''' file in text editor

|  Now type -

|  To copy the value of variable '''dollar firstVar''' to '''dollar secondVar''', type -

|  All mathematical operations like addition, subtraction, multiplication, division, can be done on these variables  

|  Switch to text editor.

| '''dollar firstVar equal to dollar secondVar equal to ten semicolon''' And Press '''Enter'''.

|  Now to print these values, type

| '''print double quote firstVar: dollar firstVar and secondVar: dollar secondVar slash n''' close double quote  '''semicolon''' press '''Enter'''.

|  Now let us add the values in the two variables.

| For this type

| '''dollar addition space equal to space dollar firstVar plus space dollar secondVar semicolon'''and Press '''Enter'''.

|  Once again, to print the value of the  variable '''addition''', type

| '''print double quote Addition is dollar addition slash n''' close double quote '''semicolon'''

| Save this file

|  To compile this file again on terminal type

| There is no syntax error so we can execute the script...

|   by typing '''perl multivar dot pl'''

 

|  This will produce an output as highlighted.

|  Now let us save this file and close it.

| There is no syntax error.

 

| So we can execute the script as '''perl multivar dot pl'''

 

| On execution the output will look like this.

| In this tutorial we have learnt,

| To Declare and Use '''scalar variables''' in '''Perl'''

|  '''Assignment'''

|  Declare a number '''variable'''.  

|  Print the '''variable''' declared.

|  Print those '''2  variables''' one after the other.

 

 

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|  Hope you enjoyed this '''Perl''' tutorial. This is Amol Brahmankar signing off.